#### Seminars - Historic

<Theme details>
##### Polyadic sets and unnatural isomorphisms
2023-03-14
Speaker: Luca Reggio (University College London, UK)
A polyadic set over a category C is a presheaf over C satisfying an appropriate amalgamation property. Polyadic sets are a discrete variant of Joyal's polyadic spaces, which are dual to Lawvere's Boolean hyperdoctrines. I will give an overview of some basic ideas and constructions concerning...

##### Van Est Theorems for Lie groupoids
2023-03-10
Speaker: Lennart Obster (CMUC, UC|UP PhD student)
TBA...

##### Moduli of twisted Higgs bundles as a degeneration of moduli of Lie algebroid connections
2023-03-08
Speaker: André Oliveira (CMUP, Univ. Trás-os-montes e Alto Douro)
Out of a given holomorphic Lie algebroid L on a compact Riemann surface X, one can consider a corresponding L-connection on a vector bundle over X. This naturally degenerates onto a (twisted) Higgs bundle on X. Via a generalization of the classical construction by Simpson of...

##### Groebner Basis
2023-03-08
Speaker: Alexander Kovacec (CMUC, Univ. Coimbra)
TBA...

##### A gentle introduction to the Hitchin fibration
2023-02-28
Speaker: Juan Sebastian Numpaque (CMUP, UC|UP PhD student)
TBA...

##### What are Lie algebroids and Lie algebroid connections?
2023-02-28
Speaker: João Nuno Mestre (CMUC, Univ. Coimbra)
TBA...

##### When are there enough isomorphisms? Representing theories by groupoids of models
2023-02-23
Speaker: Joshua Wrigley (Università degli Studi dell'Insubria, Como, Italy)
For some logical theories, the data of the theory can be reconstructed from the group of automorphisms of a "special model". For example, the theory of dense linear orders can be reconstructed from the automorphism group of the rationals (considered as a dense linear order). ...

##### Transverse densities and modular classes of Lie groupoids
2023-02-22
Speaker: João Nuno Mestre (CMUC, Univ. Coimbra)
The modular class of a Lie groupoid is a generalization of the modular class of a Lie group, which detects the failure of the Haar measure to be bi-invariant.Certain (good) functors on vector spaces, for example volume elements, and densities, lead to 1-dimensional representations of Lie...

##### Variational solution to Bernoulli type free transmission problems
2023-02-17
Speaker: Harish Shrivastava (Tata Institute of Fundamental Research, Bangalore, India)
In this seminar, I will discuss the regularity theory and some aspects related to free boundaries of variational solutions to Bernoulli type free transmission problems. We start with discussing challenges which come while proving optimal regularity of minimisers when coefficients are only...

##### Crystals, and the Berenstein-Kirillov, cacti and related groups
2023-02-15
Speaker: Olga Azenhas (CMUC, Univ. Coimbra)
Berenstein and Kirillov have introduced and studied the group generated by the Bender-Knuth involutions modulo the relations they do satisfy on semi-standard tableaux of straight shape. Halacheva has generalized the Henriques-Kamnitzer cactus group to Dynkin diagrams of classical Cartan...

##### Some aspects of enriched completely distributive lattices
2023-01-24
Speaker: Dirk Hofmann (CIDMA, Univ. Aveiro)
The topics of this talk are motivated by two classic results: firstly, the fact that "Topop is a quasi-variety" proven by Barr and Pedicchio in 1995; secondly, the identification of (constructively) completely distributive lattices as the nuclear objects in the autonomous category...

##### Pervin spaces and Frith frames: bitopological aspects and completion
2023-01-24
Speaker: Célia Borlido (CMUC, Univ. Coimbra)
A Pervin space is a set equipped with a bounded sublattice of its powerset, while its pointfree version, called Frith frame, consists of a frame equipped with a generating bounded sublattice. It is known that the dual adjunction between topological spaces and frames extends to a dual...

##### (Quasi)-Painlevé equations and Painlevé equivalence problem
2023-01-20
Speaker: Galina Filipuk (Univ. of Warsaw, Poland)
Painlevé equations are second order nonlinear differential equations solutions of which have no movable critical points (algebraic singularities). They appear in many applications (e.g., in the theory of orthogonal polynomials) but in disguise. How to find a transformation to the...

##### Extremal index and periodicity for chaotic dynamical systems
2023-01-11
Speaker: Ana Cristina Freitas (CMUP, Univ. Porto)
The extremal index appears as a parameter in Extreme Value Laws, characterising the clustering of extreme events. We apply this idea to a dynamical systems context to analyse the possible extreme value laws for the stochastic process generated by observations taken along dynamical orbits. We...

##### Computing generalized Seifert matrices for closures of colored braids
2023-01-05
Speaker: José Pedro Quintanilha (Univ. Bielefeld, Germany)
Seifert matrices have been a foundational tool in knot theory ever since they were introduced in the 1930's. They are not link invariants - in fact, the definition of a Seifert matrix for a link L depends heavily on the choice of a Seifert surface S for L and of a Z-basis of H_1(S)....

##### Tropicalizing moduli spaces
2023-01-04
Speaker: Margarida Melo (U. Roma Tre / CMUC)
In algebraic geometry, the existence of moduli spaces to parametrize certain classes of objects is of central importance. Moreover, since these moduli spaces are often not compact, the construction of modular compactifications for theses spaces is very useful, as one can study them by using...

##### On the holonomy group
2023-01-04
Speaker: Hamza Bakhouch (UC|UP PhD student)
In differential geometry, a differential structure on a topological space allows us to see locally our space like a Euclidean space. A foliation structure on a differential manifold allows us to see the manifold, locally as a family of "horizontal" (lines/planes/hyperplanes...) and...

##### On lax comma categories of ordered sets
2022-12-19
Speaker: Maria Manuel Clementino (CMUC, Univ. Coimbra)
We will analyse the behaviour of the lax comma category Ord//X, for a complete ordered set X, namely with respect to exponentiability and descent.This talk is based on joint work with Fernando Lucatelli Nunes....

##### Descent for split fibrations
2022-12-19
Speaker: Fernando Lucatelli Nunes (Utrecht Univ. & CMUC)
See attached file....

##### Examples of explicit solutions to the cubic wave equation
2022-12-16
Speaker: Giuseppe Negro (CAMGSD, IST)
We construct a two-parameter family of solutions to the focusing cubic wave equation in $\mathbb{R}^{1+3}$. Depending on the values of the parameters, these solutions either scatter to linear ones, blow-up in finite time, or exhibit a new type of unstable behaviour that acts as a threshold...

##### The congruent number problem
2022-12-14
Speaker: Nirina Albert Razafimandimby (UC|UP PhD student)
In mathematics, especially in number theory, we often encounter problems that are easy to state, but whose solution is often extremely difficult and sometimes requires sophisticated methods from other branches of mathematics. The Congruent Number Problem is one such unsolved problem that...

##### Solving integro-differential problems with the Tau method: TauToolbox
2022-12-14
Speaker: Paulo Vasconcelos (CMUP, Univ. Porto)
The spectral Tau method delivers polynomial approximations to the solution of differential problems. The method tackles both initial and boundary value problems with ease and ensures excellent error properties, whenever the solution is smooth.In this talk, the Lanczos' Tau method is examined...

##### The palindromization map
2022-12-13
Speaker: Dominique Perrin (Univ. Gustave-Eiffel, Paris-Est, France)
The palindromization map has been defined initially by Aldo de Luca in the context of Sturmian words. It was extended to the free group of rank 2 by Kassel and Reutenauer. We extend their construction to arbitrary alphabets. We also investigate the suffix automaton and compact suffix...

##### Scientific machine learning: some methods and applications
2022-12-09
Speaker:

Emmanuel Franck & Victor Michel-Dansac (Inria & IRMA, Strasbourg, France)

Machine learning performance has exploded since the beginning of the 2010s. In this talk, we propose to investigate what learning can bring in the context of scientific computing and approximation of PDEs. To that end, we will introduce two interesting frameworks:...

##### A characterisation of Lie algebras using ideals and subalgebras
2022-12-07
Speaker: Xabier García Martínez (Univ. Vigo, Spain & Vrije Universiteit Brussel, Belgium)
In this talk we will state a result characterising the variety of Lie algebras amongst all varieties of non-associative algebras. More specifically, the variety of Lie algebras is the only variety that simultaneously satisfies the following two properties: every subalgebra of a free algebra...

##### Mathematical modeling and numerical simulation in stimuli responsive drug delivery systems
2022-12-07
Speaker: José Augusto Ferreira (CMUC, Univ. Coimbra)
Stimuli responsive drug delivery systems are medical devices that are able to deliver drugs locally in the target tissue in a controlled way and without affecting the healthy tissues. The drugs are encapsulated in nanostructures that able to be safely transported to the target tissue where...

##### Scalable methods for high-dimensional inverse problems using neural networks and implicit method of moments
2022-12-02
Speaker: João M. Pereira (IMPA, Rio de Janeiro, Brazil)
I will talk about two recent projects of mine in that concern high-dimensional inverse problems. In the first project, we use machine learning tools for discovering laws and equations that govern high-dimensional datasets. Specifically, I will present two methods we...

##### The homology language of a higher-dimensional automaton
2022-11-30
Speaker: Thomas Kahl (CMUM, Univ. Minho)
Higher-dimensional automata, i.e., labeled precubical sets, are a very expressive combinatorial-topological model for concurrent systems. In this seminar, I will talk about the homology language of a higher-dimensional automaton, which is defined as the image of a labeling homomorphism from...

##### Identities and bases in hypoplactic, sylvester and Baxter monoids
2022-11-30
Speaker: Duarte Ribeiro (CMA, Univ. Nova de Lisboa)
See the attached file....

##### Duality: from theory to applications
2022-11-30
Speaker: Célia Borlido (CMUC, Univ. Coimbra)
In 1936, Marshall H. Stone proved the so-called Stone's representation Theorem for Boolean algebras, thus establishing a duality between Boolean algebras and certain topological spaces. Inspired by Stone's result, many dualities between suitable categories of topological spaces and of...

##### An introduction to the localic approach to topology
2022-11-23
Speaker: Jorge Picado (CMUC, Univ. Coimbra)
A topological space is a set of points along with a topology, a system of subsets called open sets that with the operations of union (as join) and intersection (as meet) forms a lattice with certain properties. In the localic approach to topology one forgets about points and thinks about a...

##### Riemann surfaces, line bundles and divisors
2022-11-23
Speaker: Gabriel Martinho (UC|UP PhD student)
Line bundles are fundamental objects in geometry, generalizing some properties of tangent and cotangent bundles of manifolds. In algebraic geometry, it is common to consider line bundles over compact Riemann surfaces. On the other hand, it is also frequent to make use of divisors on these...

##### Weighted inequalities restricted on the cone of monotone functions and applications in the real interpolation
2022-11-18
Speaker: Amiran Gogatishvili (Czech Academy of Sciences, Prague, Czech Republic)
We consider Hardy inequalities restricted on the cone of monotone and quasi-concave functions and we will give applications of this in the embedding of Lorentz-type spaces and in the real interpolation.  Link to access the seminar via...

##### Completeness and linearization
2022-11-16
Speaker: Matias del Hoyo (Univ. Federal Fluminense, Brazil)
Given a surjective submersion, the following are equivalent: (i) it is locally trivial, (ii) it admits a complete connection, (iii) it admits a fibered complete metric. Surjective submersions are examples of Lie groupoids, and conversely, any Lie groupoid can be regarded as a surjective...

##### Digging into fractional diffusion equations
2022-11-16
Speaker: Ercília Sousa (CMUC, Univ. Coimbra)
Diffusion models, involving differential equations with non-integer order derivatives, have lately become extremely popular because it is believed they can describe the observed reality more accurately than models based on integer order derivatives. They have been appearing in several...

##### Wave propagation in viscoelastic materials
2022-11-16
Speaker: Afonso Costa (UC|UP PhD student)
Here we present a study of a problem that describes the displacement of a wave in a viscoelastic material. To the problem are established existence, uniqueness and stability results. Furthermore, a numerical method is proposed, a semi-discrete defined over a non-uniform partition and the...

##### Alternative algebras and maps preserving products equal to fixed elements
2022-11-16
Speaker: Douglas de Araujo Smigly (Univ. São Paulo, Brazil)
See the attached file...

##### Profinite codes
2022-11-15
Speaker: Alfredo Costa (CMUC, Univ. Coimbra)
A code over the alphabet A is a nonempty subset of the free monoid over A that freely generates a free submonoid.In this talk we review some results about the topological closure of codes over A in the free profinite monoid generated by A, and present some applications of such closures to...

##### Taking verifiability seriously
2022-11-15
Speaker: Graham Manuell (CMUC, Univ. Coimbra)
Interpreting open sets as verifiable properties and continuous functions as processes helps explain many aspects of topology. However, it might appear that taking this approach completely seriously sometimes leads to conclusions that contradict known results. For instance, it might seem that...

##### High order methods for PDE: panorama and perspective
2022-11-11
Speaker: Stéphane Clain (CMUC, Univ. Coimbra)
Very high order methods enable to substantially reduce the computational effort while producing high accuracy approximations. They also provide high spectral resolution to catch very small structures with respect to the mesh parameter size. Three major issues have to be addressed to ...

##### Dirac structures and Hamiltonian inverse problem, applications to linear systems and Lotka-Volterra equations
2022-11-09
Speaker: Hassan Alishah (Univ. Minas Gerais, Brazil)
In this talk, I, first, will provide some preliminary definitions and observations on Dirac/big-isotropic structures and Hamiltonian inverse problem. Then I will present an algorithm to solve the Hamiltonian inverse problem for a given system written in the gradient form. Then I will discuss...

##### Hamilton's equations and symplectic numerical methods
2022-11-09
Speaker: Gonçalo Oliveira (UC|UP PhD student)
Hamilton's equations can be used to model many problems in the real world, and these equations could present several properties. Thus, in this talk, we are going to study numerical methods that preserve such properties, such as the Symplectic Euler Method. ...

##### Category Theory: history, basics and monads
2022-11-09
Speaker: Federico Rizzetto (UC|UP PhD student)
The aim of my seminar is to present a brief introduction to basics in category theory and to quote some applications of it. Precisely my seminar is divided into four parts. Some lines of the history of category theory, a quoting of some applications in several branches of mathematics, a...

##### Improved regularity estimates at free and fixed boundary points
2022-11-04
Speaker: Damião J. Araújo (Univ. Federal da Paraíba, Brazil)
We will discuss local regularity versus regularity estimates at free and fixed boundary points for solutions of degenerate nonlinear elliptic PDEs. We will be interested in showing how precisely the smoothness of a given solution is affected by degenerate diffusion models and free and fixed...

##### Modelling light propagation in the cornea
2022-11-02
Speaker: Milene Santos (UC|UP PhD student)
To model the incidence and reflection of light in the cornea, we can use the Maxwell's equations. In this talk, we focus on the Maxwell's equations in the time-harmonic form which translates into the Helmholtz equation. We propose a numerical method based on nodal discontinuous Galerkin...

##### Riemann's Zeta Function
2022-11-02
Speaker: Adriana Cardoso (UC|UP PhD student)
The Riemann's Zeta function is a very interesting mathematical object, due to its relation to the prime numbers and to the Riemann's Hypothesis, proposed in 1859 and still to this day unanswered. In this seminar, we will see some equivalents to the famous hypothesis, involving the...

##### 3-manifolds, knots and surfaces
2022-10-26
Speaker: João Nogueira (CMUC, Univ. Coimbra)
We will survey the motivation and history of 3-manifold topology, together with its twin subject of knot theory, giving emphasis to the importance of surfaces and groups on the understanding of these subjects. Under this framework, we will review some recent developments and guiding open...

##### A low-cost alternating projection approach for a continuous formulation of convex and cardinality constrained optimization
2022-10-21
Speaker: Evelin Krulikovski (Univ. Nova de Lisboa)
We consider convex constrained optimization problems that also include a cardinality constraint. In general, optimization problems with cardinality constraints are difficult mathematical programs which are usually solved by global techniques from discrete optimization. We assume that the...

##### Atomic length in Weyl groups
2022-10-20
Speaker: Thomas Gerber (EPFL, Lausanne, Switzerland)
Let W be the Weyl group of a finite or affine root system. It is well-known that the length of an element of W equals the number of its inversions.In this talk, I will introduce the notion of "atomic length" of an element of W and present some of its properties and applications in...

##### Symplectic cacti, virtualization and colourful reversal of Kashiwara--Nakashima tableaux
2022-10-20
Speaker: Jacinta Torres (Jagiellonian Univ., Krakow, Poland)
I will present an explicit action of the symplectic cactus group, as defined by Halacheva for the Dynkin diagram of a finite root system, on the crystal of Kashiwara-Nakashima tableaux, in terms of the virtualization map due to Baker. Additionally, I will present a "colourful"...

##### The Karoubi envelope of a semigroup
2022-10-19
Speaker: Alfredo Costa (CMUC, Univ. Coimbra)
The importance for Semigroup Theory of the Karoubi envelope of a semigroup became apparent in the 1980s with the Delay Theorem. This result fits in a framework that was since the 1960s one of the main driving forces of Semigroup Theory: the connections between semigroups and formal...

##### On split extensions of preordered groups
2022-10-18
Speaker: Maria Manuel Clementino (CMUC, Univ. Coimbra)
As shown in [1], the category OrdGrp of preordered groups and monotone group homomorphisms does not satisfy the Split Short Five Lemma, although the behaviour of split extensions in OrdGrp has some interesting facets.In this talk we will study these split extensions, focusing in particular...

##### Jónsson categories
2022-10-18
Speaker: Diana Rodelo (CMUC & Univ. Algarve)
In this work we generalise Jónsson's theorem for congruence distributive varieties of universal algebras. The linear Mal'tsev condition extracted from the ternary Jónsson terms give rise to matrix conditions Jn, n ≥ 1. We characterise regular categories C which satisfy (the...

##### Proof of three conjectures by M.E.H. Ismail
2022-10-07
Speaker: Dieudonne Mbouna (University of Almeira, Spain)
In this talk we expose the theory of classical orthogonal polynomials on lattices and we use this to give positive answers to three conjectures posed by M. E. Ismail in his monograph Classical and quantum orthogonal polynomials in one variable, Cambridge University Press, 2005....

##### Translating solutions and non-parametric mean curvature flow with prescribed contact angle in Riemannian products
2022-09-30
Speaker: Ilkka Holopainen (Univ. of Helsinki, Finland)
Abstract is attached....

##### Asymptotic behavior and stability of solutions in differential equations of mixed type
2022-09-23
Speaker: Sandra Pinelas (DCEE, Academia Militar)
In this study, some new results are obtained on  stability analysis of a mixed type differential equation. These results were obtained by using an appropriate real root of the characteristic equation. Moreover, by the use of two appropriate distinct real roots of the...

##### On categorical conditions in the semi-abelian context
2022-09-13
Speaker: James Gray (Stellenbosch University, South Africa)
The purpose of this talk is three-fold. To give an overview of categorical conditions that hold for the categories of groups and Lie algebras. To explain how a single categorical condition gives rise to all of these conditions. To explain which implications do and do not hold between these...

##### Algebraic geometry and tangent categories
2022-09-13
Speaker: Geoff Cruttwell (Mount Allison University, Canada)
Tangent categories, first defined by Jiri Rosicky, are a categorical structure which encompasses not only ordinary differential geometry, but also synthetic differential geometry and notions of differentiation coming from computer science.In this talk, I'll discuss how the category of affine...

##### Combinatorial properties of link quandles
2022-07-27
Speaker: Manpreet Singh (CAMGSD, IST, Univ. Lisboa)
Classical knot theory is the study of smooth embeddings of circles in the 3-sphere up to the ambient isotopy. One of the fundamental problems in this field is the classification of knots, for which one needs invariants. The fundamental group of a knot complement space is a...

##### When measurable spaces don't have enough points
2022-07-26
Speaker: Paolo Perrone (University of Oxford, UK)
In topology, a space is called sober if every irreducible closed subset is the closure of a unique point.One can express this concept in terms of the lower Vietoris monad, which assigns to a topological space X the space HX of its closed subsets.Given a space X, we can form a parallel pair...

##### The definition of pre-cohesive map in perspective
2022-07-26
Speaker: Matías Menni (Universidad Nacional de La Plata, Argentina)
Stressing topological/geometric intuition in hyperconnected geometric morphisms, we characterize the pre-cohesive ones among them. Moreover, we show that pre-cohesive maps are molecular over boolean bases....

##### Nonlinear smoothing by the infinite normal form reduction method
2022-07-22
Speaker: Jorge Drumond Silva (IST, Lisboa)
Many nonlinear dispersive partial differential equations exhibit a phenomenon where the nonlinear part of the evolution, in the Duhamel integral formula, is slightly more regular than the purely linear evolution, for the same initial data. This is usually called nonlinear smoothing and is...

##### Artin glueings as semidirect products
2022-07-21
Speaker: Graham Manuell (CMUC, Univ. Coimbra)
Artin glueings provide a way to reconstruct a locale (or topos) from a closed sublocale (subtopos) and its open complement. In this talk I will explain how Artin glueings of frames can be described as weakly Schreier split extensions in the category of frames and finite-meet-preserving maps....

##### Terms and derivatives of polynomial functors via negation
2022-07-21
Speaker: Charles Walker (Masaryk Univ., Brno, Czech Republic)
Given a locally cartesian closed category E with a strict initial object, we define a negation operator on E and show that this yields a dense-closed orthogonal factorization system on E.Using this negation operator (and now assuming E has disjoint finite sums) we define both terms and...

##### The birth of Euclidean geometry (and mathematics) & the birth of non-Euclidean geometry
2022-07-18
Speaker: Dénes Nagy (Australian Catholic Univ., Melbourne, Australia)
TBA...

##### On the conjugation action for quantum GL(n)
2022-07-13
Speaker: Stephen Donkin (Univ. of York, UK)
The algebra of polynomial functions on n by n complex matrices that are constant on conjugacy classes is the free polynomial algebra on the functions giving the coefficients of the characteristic polynomial. Here we give a similar description of the algebra of invariants C(G), for the action...

##### Ramsey theory for infinite words
2022-07-06
Speaker: Manuel Silva (Univ. Nova de Lisboa)
We will discuss several ramsey-type results in combinatorics on words. In one of the results, it is proved that the existence of powers or anti-powers is an unavoidable regularity for sufficiently long words. An abelian version, where we count the frequency of each letter, is conjectured to...

##### Lie groupoids for PDE analysis
2022-06-29
Speaker: Ivan Beschastnyi (CIDMA, Univ. Aveiro)
Lie groupoids are effective tools for studying singular spaces, which explains their popularity in Poisson geometry, foliation theory and other fields of mathematics. They serve as natural desingularisations and come with an array of useful tools. In recent years, it was understood that...

##### K dissimilar paths
2022-06-24
Speaker: Marta Pascoal (Politecnico di Milano, CMUC/University of Coimbra, and INESC Coimbra)
The aim of this talk is to address the determination of K alternative paths linking two given nodes in a network. In particular the paths are expected to minimize simultaneously a linear objective function and a similarity measure based on the overlaps between them. The problem is modelled...

##### Characterization of maps
2022-06-08
Speaker: Bruno Leonardo Macedo Ferreira (Federal University of Technology-Paraná, Brazil)
See the attached file....

##### The Gelfand problem for the infinity Laplacian
2022-06-03
Speaker: Fernando Charro (Wayne State University, Detroit, USA)
attached....

##### Ensino e Investigação de Matemática em Angola: conquistas e desafios
2022-06-01
Speaker: Maria de Natividade (Univ. Agostinho Neto, Luanda, Angola)

##### Hölder and maximal regularity for Hamilton-Jacobi equations
2022-05-27
Speaker: Marco Cirant (University of Padova, Italy)
I will discuss some results on the regularity of solutions to semilinear elliptic equations of Hamilton-Jacobi type. I will in particular focus on the Hölder regularity of solutions, and the problem of L^p maximal regularity, developing two (different?) approaches based on the Bernstein...

##### Associativity and the co-smash product
2022-05-24
Speaker: Tim Van der Linden (Université Catholique de Louvain, Belgium)
The aim of this talk is to sketch some ideas in joint work-in-progress with Ülo Reimaa and Corentin Vienne. The original question we set out to answer was to characterise when the objects in a variety of algebras over a field K have a multiplication that is associative. What we found is...

##### An invitation to double categories and double fibrations
2022-05-24
Speaker: Martin Szyld (Dalhousie University, Canada)
Joint work with Geoff Cruttwell, Michael Lambert, and Dorette Pronk I will present our work on the notion of fibration for double categories [*]. I will not assume prior knowledge about double categories. Instead, I will present during the talk some basic aspects of the theory of double...

##### Trajectory optimization in L^1 and applications to some new Mean Field Games
2022-05-20
Speaker: Filippo Santambrogio (Université Lyon 1, France)
I will present some regularity results on a variational problem for curves of probability densities where their velocity is penalized in terms of the L<sup>1</sup> (or total variation) norm, of the time derivative. This is motivated by a new class of Mean Field Games whose goal...

##### Nonlocal capillarity theory
2022-05-13
Speaker: Enrico Valdinoci (Univ. of Western Australia, Perth, Australia)
We describe some recent results motivated by a nonlocal theory of capillarity, as related to the formation of droplets due to long-range interaction potentials. We will discuss the notion of contact angle in this setting, considering a nonlocal version of the classical Young's Law, together...

##### A priori estimate for a fully nonlinear problem depending on the gradient
2022-05-06
Speaker: Disson dos Prazeres (Univ. Federal de Sergipe, Brazil)
We will talk about an a priori estimate for positive solutions of some degenerate fully nonlinear elliptic equations where the nonlinearity on the RHS depends on x, u, and ∇u. As a consequence, we use the a priori estimate to establish an existence result....

##### Geometry of mechanical systems with constraints and impacts
2022-05-04
Speaker:

Anthony Bloch (Univ. of Michigan, USA)

In this talk I will discuss some of the general theory of mechanical (Lagrangian and Hamiltonian) system on manifolds and in particular discuss how the dynamics is affected when there are nonholonomic (nonintegrable) constraints and impacts. I will discuss conservation laws, conservation of...

##### The combinatorics of Kostka polynomials
2022-05-04
Speaker: Cédric Lecouvey (Univ. Tours, France)
In representation theory of the Lie algebras, each irreducible representation decomposes into weight spaces. The dimensions of these subspaces can be computed via the Weyl character formula and admit interesting quantizations. The polynomials so obtained have a simple definition and numerous...

##### On the existence of minimizers for Hardy inequalities
2022-04-29
Speaker: Yehuda Pinchover (Technion, Israel Institute of Technology)
TBA      ...

##### Up to the boundary gradient estimates for solutions to nonlinear free boundary problems with unbounded measurable ingredients
2022-04-22
Speaker: Diego R. Moreira (Universidade Federal do Ceará, Brazil)
In this talk, we discuss recent advances on up to the boundary gradient estimates for viscosity solutions of free boundary problems governed by fully nonlinear and quasilinear equations with unbounded coefficients. We present the new Inhomogeneous Pucci Barriers as new elements for the...

##### Weak adjoints and colimits in the homotopically enriched setting
2022-04-13
Speaker: John Bourke (Masaryk Univ., Brno, Czech Republic)
In category theory, one often encounters weak colimits as well as ordinary colimits. Lack and Rosicky [1] realised that can be viewed as instances of a common concept, if we work with categories enriched over a base V equipped with an appropriate class of morphisms E. Dealing with...

##### In search for an algebraically sound notion of a subobject in the dual of a topos
2022-04-05
Speaker: Zurab Janelidze (Stellenbosch Univ., South Africa)
A noetherian form over a category is a faithful bifibration over it, whose fibres are lattices, and which satisfies certain self-dual axioms ensuring the validity of homomorphism theorems (as stated relative to the form) from abstract algebra, such as the isomorphism theorems and homological...

##### Sublocales of the frame of fitted sublocales
2022-04-05
Speaker: Anna Laura Suarez (Université Côte d'Azur, France)
See the attached file. ...

##### Functorial approach to rank functions
2022-03-30
Speaker: Teresa Conde (Univ. of Stuttgart, Germany)
Motivated by the work of Cohn and Schofield on Sylvester rank functions on rings, Chuang and Lazarev have recently introduced the notion of a rank function on a triangulated category. A rank function is a nonnegative real-valued, additive, translation-invariant function on the objects of a...

##### A discrete duality for algebras of partial functions for a foundational signature
2022-03-29
Speaker: Célia Borlido (CMUC, Univ. Coimbra)
The study of algebras of partial functions is an active area of research that investigates collections of partial functions and their interrelationships from an algebraic perspective. The partial functions are treated as abstract elements that may be combined algebraically using various...

##### Semibiproducts of magmas and semigroups
2022-03-29
Speaker: Nelson Martins-Ferreira (IP Leiria)
Semibiproducts are introduced as a generalization of biproducts. Classically, biproducts are defined in the context of additive categories ([1], p. 250). The appropriate context in which the notion of semibiproduct makes sense is the one of a concrete category over sets with maps and...

##### Central extensions of associative algebras
2022-03-22
Speaker: George Janelidze (University of Cape Town, South Africa)
We compare descriptions of central extensions of associative R-algebras, for a commutative ring R, defined with respect to two reflections: to R-modules (equipped with the zero multiplication) and to commutative R-algebras. In both cases, the results are as expected. However, while the first...

##### Multiplicative lattices, groups, braces
2022-03-22
Speaker: Alberto Facchini (Università di Padova, Italy)
The multiplicative lattices we will consider are those defined in [Facchini, Finocchiaro and Janelidze, Abstractly constructed prime spectra, Algebra universalis 83(1) (published only in February 2022)]. Multiplicative lattices yield the natural setting in which several basic mathematical...

##### Recent results on planar predator-prey and competitive models with seasonality
2022-03-11
Speaker: Carlota Rebelo Gonçalves (Univ. de Lisboa)
TBA...

##### Minimizing movements for mean curvature flow of partitions
2022-03-04
Speaker: Shokhrukh Kholmatov (Univ. Vienna, Austria)
In this talk I would like to discuss about a weak solution of mean curvature flow of partitions of space, defined via a minimizing movements approach introduced by Almgren-Taylor-Wang and De Giorgi. The talk is based on the joint work with Giovanni Bellettini and Antonin Chambolle....

##### G-structures on orbifolds
2022-03-04
Speaker: Sebastián Daza (PhD student, CMUC)
Orbifolds allow us to model spaces like manifolds, but with good singularities on them, encoded by finite group actions. If these actions are effective, the frame bundle of an orbifold has a manifold structure. Besides, a linear geometric structure induces a symmetry (group action) on the...

##### Blow-ups of Lie groupoids and Lie algebroids
2022-03-04
Speaker: Lennart Obster (PhD student, CMUC)
In the presentation, we will go into the (projective) blow-up construction for Lie groupoids and Lie algebroids. In the literature, there are different methods to be found on how to do this, especially for Lie groupoids. The main goal of the talk will be to explain the blow-up construction...

##### Pointwise multiplications in Morrey spaces
2022-02-25
Speaker: Yoshihiro Sawano (Chuo Univ., Japan)
The goal of this talk is to discuss the pointwise multiplication properties of Morrey spaces. First, as a model case, we consider the Olsen inequality. Second, we discuss how to specify the pointwise multiplier spaces. Our method carries over to weak spaces. This is a joint work mainly...

##### Deformations of symplectic foliations via Dirac geometry and L-infinity algebras
2022-02-16
Speaker: Alfonso Tortorella (CMUP, Univ. Porto)
In this talk, based on joint work with Stephane Geudens and Marco Zambon, we develop the deformation theory of symplectic foliations, i.e. regular foliations equipped with a leafwise symplectic form. The main result is that each symplectic foliation is attached with a cubic L-infinity...

##### Symmetric decompositions, triangulations and real-rootedness
2022-02-16
Speaker: Eleni Tzanaki (Univ. Crete, Greece)
A triangulation of a simplicial complex Δ is said to be uniform if the f-vector of its restriction to a face of Δ depends only on the dimension of that face. The notion of uniform triangulation was introduced by Christos Athanasiadis in order to conveniently unify many well...

##### Topology for internal pre-orders: focus on complete regularity
2022-02-15
Speaker: Walter Tholen (York University, Canada)
Treating the ultrafilter monad for sets as a role model, under modest hypotheses on the two parameters involved, we consider some topological notions for T-pre-orders, internal to a category C that comes equipped with a monad T. We call them T-spaces in C, present a rudimentary theory for...

##### Nonlinear versions of the Banach-Schauder open mapping theorem
2022-02-04
Speaker: Sauli Lindberg (Univ. Helsinki, Finland)
I will present nonlinear versions of the Banach-Schauder open mapping theorem. They apply to constant-coefficient PDEs (and initial value problems) that are scaling-invariant and preserved under weak-* convergence. As a first application, I will present a partial result on a long-standing...

##### Regularity theory: from PDE to interfaces and beyond
2022-01-28
Speaker: Edgard Pimentel (CMUC)
Operators with solution-dependent discontinuities give rise to interfaces or free boundaries. In this context, two fundamental questions appear. First, one is interested in the regularity properties of the solutions across the free boundary. Then the analysis focuses on the interfaces and...

##### How can the Cerebral Aneurysms near-wall region be investigated?
2022-01-28
Speaker: Iolanda Velho (CEMAT, Univ. Lisboa)
Cerebral Aneurysms (CA) represent a frightening and silent threat with a high prevalence and mortality rate. Despite several studies, the mechanisms of aneurysm development are not fully understood. Nonetheless, hemodynamic and biochemical factors, especially related to the vessel wall, are...

##### Injectivity of induction in Lie theory
2022-01-26
Speaker: Thomas Gerber (EPFL, Lausanne, Switzerland)
Given two isomorphic representations of a simple lie algebra over ℂ induced from two irreducible representations V and W of a parabolic subalgebra, what can be said about V and W? In this talk, we consider the case of the general linear and symplectic Lie algebras. We show that the...

##### Weak factorization systems in locally presentable categories
2022-01-25
Speaker: Jiří Rosický (Masaryk Univ., Brno, Czech Republic)
We will deal with cofibrantly generated, accessible and fibrantly generated weak factorization systems in locally presentable categories.  The talk is mostly based on a joint work with Sean Cox. ...

##### Endomorphisms of hyperbolic groups
2022-01-25
Speaker: André Carvalho (Univ. Porto, Portugal)
The Bounded Reduction Property (or Bounded Cancellation Lemma) was introduced by Cooper for automorphisms of free groups and has played an important role in the dynamical study of endomorphisms of (virtually) free groups since then.In this talk, we will present some (equivalent) geometric...

##### The two-sided Karnofsky-Rhodes expansion of a semigroup
2022-01-24
Speaker: Alfredo Costa (CMUC, Univ. Coimbra)
In semigroup theory, the term "expansion" refers to an endofunctor in the category of semigroups, equipped with a natural transformation to the identity functor which is surjective in each object.There is a big number of expansions with names of semigroup theorists, a reflection of...

##### The notion of farness in uniform frames and its underlying Galois adjunction
2022-01-24
Speaker: Ana Belén Avilez (PhD student, CMUC)
We will explore the notion of farness in (pre-)uniform frames and the role it plays in characterizing uniform continuity of real-valued functions. We will describe the relation of farness between elements in a frame in terms of Galois adjunctions. This will allow us to present a...

##### Rate of blow up in the thin obstacle problem
2022-01-20
Speaker: Hui Yu (National University of Singapore)
TBA...

##### Relative dominant dimension and quality of split quasi-hereditary covers.
2022-01-19
Speaker: Tiago Cruz (Univ. Stuttgart, Germany)
Dominant dimension of a finite-dimensional algebra A is a homological invariant measuring the connection between module categories A-mod and B-mod, where B is the endomorphism algebra of a faithful projective-injective A-module.In this talk, we will discuss generalisations of dominant...

##### A multi-scale biological description with application to autoimmune diseases
2022-01-14
Speaker:

Ana Jacinta Soares (CMAT, Univ. Minho)

Biological systems are usually described at the macroscopic level, by considering the relevant interacting populations that are involved in the system. However, it is well known that a detailed description at the cellular level could be more appropriate in understanding the complex...

##### Simple modules over skew polynomial rings
2022-01-13
Speaker: Paula Carvalho (CMUP, FCUP)
We consider the structure of modules over Noetherian rings. A Noetherian ring S whose simple modules have the property that their finitely generated essential extensions are Artinian is said to satisfy property (⋄). For commutative Noetherian rings the validity of (⋄) is due to...

##### Non-orientable surfaces in 4-dimensional manifolds and rectangles inscribed in Jordan curves
2022-01-12
Speaker: Peter Feller (ETH, Switzerland)
Toeplitz asked whether every Jordan curve in the Euclidean plane contains 4 points that form the corners of a square? More generally, what about the corners of a rectangle with prescribed aspect ratio? The latter question was recently answered by Greene-Lobb for smooth Jordan curves, but...

##### Potent preservers of incidence algebras
2022-01-12
Speaker: Mykola Khrypchenko (Univ. Federal de Santa Catarina, Brazil)
Let X be a finite connected poset and F a field. Denote by I(X,F) the incidence algebra of X over F. We describe bijective linear maps from I(X,F) to I(X,F) which preserve k-potency, where k is a fixed integer greater than 1. The case k=2 (idempotent preservers) is treated for arbitrary F,...

##### A degenerate fully nonlinear free transmission problem with variable exponents
2021-12-17
Speaker: David Jesus (PhD student, CMUC)
In this talk we will discuss optimal regularity for equations with a degeneracy rate which varies in a discontinuous fashion over the domain. Moreover, this discontinuity depends in an implicit way on the solution itself. We introduce the notion of pointwise sharp regularity which requires...

##### A quantum system with a non-Hermitian Hamiltonian
2021-12-16
Speaker: Natália Bebiano (CMUC, Univ. Coimbra)
In the last decades non-Hermitian operators with real eigenvalues appeared in Quantum Mechanics (QM) and in other areas of Physics, e.g. Quantum Optics, Quantum Fluid Dynamics, and Quantum Field Theory, just to mention a few. We discuss the quantum mechanical setting of a system described...

##### Functions with small and large spectra as (non)extreme points
2021-12-10
Speaker: Konstantin Dyakonov (ICREA & Universitat de Barcelona, Spain)
Let $\Lambda$ be a subset of $\mathbb Z_+:=\{0,1,2,\dots\}$, and let $H^\infty(\Lambda)$ denote the space of bounded analytic functions $f$ on the unit disk whose coefficients $\widehat f(k)$ vanish for $k\notin\La$. Assuming that either $\Lambda$ or $\mathbb Z_+\setminus\Lambda$ is finite,...

##### Monads on the category of metric spaces
2021-12-07
Speaker: Jirí Adámek (Technische Universität Braunschweig, Germany)
The category Met of metric spaces and nonexpanding maps is locally countably presentable in the enriched sense. It follows from the work of Kelly and Power that for countably accessible monads T on Met the category of algebras can be described as an equational category of S-algebras for a...

##### Lax epimorphisms and the associated factorization
2021-12-07
Speaker: Lurdes Sousa (CMUC and IP Viseu)
Lax epimorphisms (also called co-fully-faithful morphisms) are a 2-dimensional version of epimorphisms; in a 2-category A they are precisely the 1-cells f making A(f,C) fully faithful for all objects C. In this talk, several features of lax epimorphisms will be presented. We show that any...

##### Strain and stress-rate type viscoelastic models in the context of implicit constitutive theory
2021-12-03
Speaker:

Yasemin Sengul (Cardiff University, UK)

In the constitutive equations for the classical viscoelastic models, stress tensor is expressed in terms of the strain tensor and its time derivative. However, the classical elastic and viscoelastic models are incapable of explaining the phenomena when the stress is big and the strain is...

##### Studying topology via ultrafilter convergence, categorically
2021-11-30
Speaker: Maria Manuel Clementino (CMUC / Univ. Coimbra)
Inspired on the role of ultrafilter convergence in topological spaces, we will present extensions of several topological notions and results to the more general setting of monad-quantale-enriched categories....

##### When are epimorphisms of profinite groups surjective?
2021-11-30
Speaker: Herman Goulet-Ouellet (PhD student, CMUC)
After a brief historical survey, we give a positive answer for full subcategories of profinite groups corresponding to Melnikov formations. We proceed to deduce that epimorphisms of pronilpotent groups are surjective. Finally, we discuss some negative examples and open problems....

##### Convexity and PDEs
2021-11-25
Speaker: Julio D. Rossi (Universidad de Buenos Aires, Argentina)
TBA...

##### An algebraic-topological approach to the classification of formal languages
2021-11-25
Speaker: Jorge Almeida (CMUP, FCUP)
Pervasive in mathematical linguistics and computer science, (formal) languages present many interesting and difficult problems. Various mathematical theories have been developed to deal with them. Of particular importance is the classification of languages in various classes of interest,...

##### The AIM Conjecture
2021-11-23
Speaker: Michael Kinyon (University of Denver, USA)
A long-standing open problem in loop theory has been to show that a loop with abelian inner mapping group is nilpotent of class at most 3. In this talk, I will describe the affirmative solution to this problem. No background in quasigroups or loops is needed, just some familiarity with what...

##### A new diagonal separation and its relations with the Hausdorff property
2021-11-23
Speaker: Igor Arrieta (PhD student, CMUC)
Let P be a property of subobjects relevant in a category C. An object X in C is P-separated if the diagonal in X × X has P; thus e.g. closedness in the category of topological spaces (resp. locales) induces the Hausdorff (resp. strong Hausdorff) axiom. In this talk we consider the...

##### Representations of fundamental groups of surfaces
2021-11-18
Speaker: Peter Gothen (CMUP, FCUP)
We consider representations of the fundamental group of a closed surface in the group SL(2,R). To each such representation one can associate an integer invariant called the Toledo invariant. A theorem of J. Milnor says that the absolute value of the Toledo invariant is less than or equal to...

##### Dynamical implications of convexity beyond dynamical convexity
2021-11-17
Speaker: Leonardo Macarini (IST, Portugal)
We will show sharp dynamical implications of convexity on symmetric spheres that do not follow from dynamical convexity. It allows us to furnish new examples of dynamically convex contact forms that are not equivalent to convex ones via contactomorphisms that preserve the symmetry. Moreover,...

##### On simple 15-dimensional Lie algebras in characteristic 2
2021-11-17
Speaker: Pasha Zusmanovich (Univ. Ostrava, Czech Republic)
Classification of finite-dimensional Lie algebras over a field of characteristic 2 is a widely open problem. We will discuss a certain 15-dimensional such algebra, first appearing in the works of Skryabin. It possesses a number of interesting properties which may be typical for a certain...

##### Entropy-Transport distances between measures and metric measure spaces
2021-11-12
Speaker: Nicolò De Ponti (SISSA, Trieste, Italy)
See the attached file ...

##### A glance at Poisson manifolds, Courant algebroids and Lie-infinity algebras
2021-11-12
Speaker: Joana Nunes da Costa (CMUC, Univ. Coimbra)
The goal of the talk is to give an overview of some aspects of Poisson geometry. I will start with the definition of Poisson manifold, then I will introduce Courant algebroids. Finally, I will present recent topics where I've been working on, related to Courant algebroids and Lie-infinity...

##### 3-manifolds, knots and surfaces
2021-11-11
Speaker: João Nogueira (CMUC, Univ. Coimbra)
We will survey the motivation and history of 3-manifold topology, together with its twin subject of knot theory, giving emphasis to the importance of surfaces and groups on the understanding of these subjects. Under this framework, we will review some recent developments and guiding...

##### The regularity of Eulerian ideals
2021-11-10
Speaker: Jorge Sentieiro Neves (CMUC, Univ. Coimbra)
The Eulerian ideal of a graph establishes yet another bridge between algebra and combinatorics. It encodes much information about the graph: its generators can be related to the Eulerian subgraphs with an even number of edges and, for a fixed monomial order, the associated standard...

##### Relaxed solutions for incompressible inviscid flows: A variational and gravitational approximation to the initial value problem
2021-11-05
Speaker: Ivan Moyano (University of Nice Sophia Antipolis, France)
Following Arnold's geometric interpretation, the Euler equations of an incompressible fluid moving in a domain D are known to be the optimality equation of the minimizing geodesic problem along the group of orientation and volume preserving diffeomorphisms of D. This problem admits a...

##### Enriched functional limit theorems for chaotic dynamics and heavy tailed observables
2021-11-04
Speaker: Jorge Freitas (CMUP, FCUP)
We consider stochastic processes arising from chaotic systems by evaluating an heavy tailed observable function along the orbits of the system. We prove the convergence of a normalised sum process to a Lévy process with excursions, designed to describe the oscillations observed during...

##### Families of polytopes with rational linear precision in higher dimensions
2021-11-03
Speaker: Eliana Duarte (CMUP, Univ. Porto)
Polytopes with rational linear precision are of interest in the Geometric Modeling community because of their approximation properties and it is an open question to classify them in dimension d > 2. This classification question is closely related to discrete statistical models with...

##### Monoid extensions and the Grothendieck construction
2021-10-28
Speaker: Graham Manuell (CMUC)
It is well known to category theorists that the Schreier theory of group extensions can be understood in terms of the Grothendieck construction on indexed categories, but the case of monoid extensions is seldom mentioned. In this talk I will describe how the classification of Schreier and...

2021-10-28
Speaker: Carlos Fitas (PhD student, CMUC)
After recalling a few fundamental notions about V-Cat, V-Rel and V-Dist, where V is a quantale, we will present two new characterizations of the submonads of the presheaf monad: one in terms of a special class of V-distributors; and another as those monads which are fully (BC)*, lax...

##### Why I like noncommutative algebra: a tour of symmetry, geometry and mathematical physics
2021-10-28
Speaker: Samuel Lopes (CMUP, FCUP)
I will start by motivating the study of noncommutative algebra and representation theory through examples rooted in symmetry, geometry and mathematical physics. Then I will talk about more specific aspects of my research interests....

##### Quinn Finite Total Homotopy TQFT as a once-extended TQFT
2021-10-27
Speaker: João Faria Martins (Univ. Leeds, UK)
Quinn Finite Total Homotopy TQFT is a TQFT that works in any dimension and that depends on the choice of a homotopy finite space $B$ (e.g. $B$ can be the classifying space of a finite group or of a finite 2-group). I will report on ongoing joint work with Tim Porter on once-extended versions...

##### On the lattice of restricted subalgebras of a restricted Lie algebra
2021-10-27
Speaker: Pilar Paez-Guillán (Univ. Santiago de Compostela, Spain)
Historically, the question of how far the properties of the subgroup lattice of a group G determine those of G has been extensively studied. Similar questions have been formulated for Lie algebras and restricted Lie algebras.In this talk, we will give a general characterization for...

##### From Krohn-Rhodes theory to Markov chains
2021-10-21
Speaker: Pedro Silva (CMUP, FCUP)
In the early sixties, Krohn-Rhodes theory became a cornerstone of both finite semigroup theory and automata theory. The theory expanded subsequently in different directions, including the infinite setting and applications to the theory of Markov chains. The results mentioned are joint work...

##### Algebraic geometry with computer algebra
2021-10-14
Speaker: Carlos Rito (CMUP)
The goal of the talk is to highlight the usefulness of modern computer algebra tools in the study of more classic algebraic geometry problems. I will give some examples related to my research on Schoen surfaces, Godeaux surfaces and the canonical map of surfaces of general type....

##### A non-variational approach for the porous medium equation
2021-10-14
Speaker: Makson Santos (USP, São Carlos, Brazil)
...

##### On the ternary commutator I: Exact Mal'tsev categories
2021-10-12
Speaker: Cyrille Sandry Simeu (UCLouvain, Belgium)

##### An orthogonal approach to algebraic weak factorisation systems
2021-10-12
Speaker: John Bourke (Masaryk Univ., Czech Republic)
Factorisation systems (both weak and strong) are commonly defined as consisting of two classes of maps satisfying a certain orthogonality relation and a factorisation axiom. The standard definition of algebraic weak factorisation system, involving comonads and monads, is rather different. ...

##### Orthogonal symmetric matrices and joins of graphs
2021-09-22
Speaker: Helena Smigoc (Univ. College Dublin, Ireland)
We ask when is the join of two (possibly disconnected) graphs G and H the pattern of an orthogonal symmetric matrix. A notion of compatibility for multiplicity matrices gives rise to a necessary condition. To address sufficiency, we introduce generic realisability that generalises the...

##### Point-free measures: a localic approach to measure theory
2021-09-21
Speaker: Raquel Bernardes (PhD student, CMUC)
Motivated by the fact that σ-locales generalize measurable spaces and seeking to overcome some restrictions of measure theory, Alex Simpson [1] proposed an approach to measure theory in the framework of point-free topology. This talk will be a general survey of that approach while...

##### Effective descent in internal multicategories
2021-09-21
Speaker: Rui Prezado (PhD student, CMUC)
The Bénabou-Roubaud theorem [BR70] and Beck's monadicity theorem allow us to characterize effective descent morphisms in locally cartesian closed categories; these are exactly the pullback-stable regular epimorphisms. However, characterization of effective descent morphisms is far...

##### Esakia duality and its connection with pointfree Pervin spaces
2021-09-14
Speaker: Anna Laura Suarez (Université Côte d'Azur, France)
Frames are complete Heyting algebras, but frame maps need not preserve the Heyting arrow. Those maps that preserve it are called open maps. Using the classical adjunction between frames and spaces, one can show that frames with open maps are dual to topological spaces with maps satisfying a...

##### Deciding implications of matrix properties
2021-09-14
Speaker: Michael Hoefnagel (Stellenbosch Univ., South Africa)
Matrix properties were first introduced by Z. Janelidze in 2006, as a class of exactness properties that may be represented by (extended) matrices of terms in an algebraic theory. In the simplest case, i.e., when the given algebraic theory is the algebraic theory of sets, matrix properties...

##### Lax factorisation systems and categories of partial maps
2021-07-20
Speaker: Leonardo Larizza (PhD student, CMUC)
Factorisation systems describe morphisms in a category by factorising them into pairs of composable morphisms. Their definition depends on an orthogonality relation between morphisms, which entails the existence of some diagonal morphisms for certain squares. In this seminar we present the...

##### Split extensions of bialgebras
2021-07-20
Speaker: Florence Sterck (UCLouvain, Louvain-la-Neuve)
In the category of groups, split extensions have a lot of interesting properties. One of them is the fact that the category of split extensions is equivalent to the category of group actions. Unfortunately, this does not hold in any category, for example the category of monoids does not have...

##### Elliptic regularity for some degenerate equations
2021-07-16
Speaker: Héctor A. Chang-Lara (CIMAT, Mexico)
...

##### Preordered actions of preordered monoids
2021-07-15
Speaker: Manuela Sobral (CMUC, Univ. Coimbra)
Definitions and results on preordered monoids and Schreier split epimorphisms of monoids will be recalled in order to replicate the equivalence between Schreier split extensions of monoids and monoid actions in an appropriate subcategory of the category of preordered monoids....

##### Continuity of localic maps and localization morphisms
2021-07-15
Speaker: Jorge Picado (CMUC, Univ. Coimbra)
By definition, a map between topological spaces is continuous if preimages of open sets are open or, equivalently, preimages of closed sets are closed. Can one get similar characterizations for localic maps between locales? The characterization of localic maps in terms related to continuity...

##### Eulerian polynomials via the Weyl algebra action
2021-07-07
Speaker: José Agapito Ruiz (Univ. Lisboa)
We obtain a generalization of the Worpitzky identity and new recursive formulas for a family of polynomials that include the classical Eulerian polynomials, using the action of the Weyl algebra on the geometric series and the framework of rook placements on Ferrers boards for combinatorial...

##### Regularity for C^{1,alpha} interface transmission problems
2021-07-01
Speaker: María Soria-Carro (UT Austin, USA)
...

##### Polynomial identities and central polynomials: their growth
2021-06-23
Speaker: Carla Rizzo (Univ. Palermo, Italy)
A central polynomial of an algebra A is a polynomial f in non-commutative variables that takes central values when evaluated in A. In case it vanishes in A, f is called a polynomial identity of A, otherwise f is a proper central polynomial of A. The purpose of this talk is to survey some old...

##### Symplectic left and right keys - Type C Willis' direct way
2021-06-23
Speaker: João Miguel Santos (PhD student, CMUC)
The right and left key maps for Kashiwara-Nakashima tableaux are used to describe type C Demazure and opposite Demazure crystals, respectively. For instance, Fu-Lascoux non-symmetric Cauchy kernels expand into products of opposite Demazure characters and Demazure atoms. These key maps are...

##### The category of Frith frames
2021-06-22
Speaker: Célia Borlido (CMUC, Univ. Coimbra)
A Frith frame is a frame equipped with a join-dense bounded sublattice. In this talk we will see that Frith frames and suitable morphisms form a category Frith which is equivalent to the category of transitive and totally bounded quasi-uniform frames. This equivalence provides a very simple...

##### Generalized quantale-enriched categories: a digression
2021-06-22
Speaker: Maria Manuel Clementino (CMUC, Univ. Coimbra)
This is an informal digression through the study, of the last two decades, of (generalized) quantale-enriched categories, aiming to present both results and remaining open problems on exponentiability and descent theory....

##### The optimal transport problem: regularity (and existence)
2021-06-17
Speaker: Yash Jhaveri (Columbia University, USA)
...

##### The first cohomology object in semi-abelian categories
2021-06-15
Speaker: James Gray (Stellenbosch Univ., South Africa)
We show that there is a natural notion of internal crossed homomorphism object of a split extension, defined as the representing object of a certain functor. Using these objects one can construct the first internal cohomology object of a split extension. We show that although these objects...

##### The reflexive completion in context
2021-06-15
Speaker: Tom Leinster (University of Edinburgh, Scotland)
For a small category A, Isbell conjugacy defines an adjunction between the functor categories [A^op, Set] and [A, Set]^op. The invariant part of this adjunction (that is, its category of fixed points) is called the reflexive completion of A.I will describe some results relating the reflexive...

##### Generalizations of the Fourier transform and their applications
2021-06-11
Speaker: Rita Guerra (CMUC)
In this talk, we consider a new generalization of the Fourier transform, depending on four complex parameters and all the powers of the Fourier transform. This new transform is studied in some Lebesgue spaces. We begin with the characterization of each operator by its characteristic...

##### Torsion pairs and Ringel duality for Schur algebras
2021-06-09
Speaker: Karin Erdmann (Univ. of Oxford, UK)
A finite-dimensional quasi-hereditary algebra  has a Ringel dual which is again quasi-hereditary. For blocks of  both the classical and quantum Schur algebras S(2,r) and Sq(2,r) we show they are Morita equivalent to their Ringel duals if they contain 2pk simple modules. This uses a...

##### Categorical aspects of the non-abelian tensor product
2021-05-25
Speaker: Tim Van der Linden (UCLouvain, Belgium)
We give an overview of joint work with Davide di Micco on an approach to the Brown-Loday non-abelian tensor product in the context of semi-abelian categories. We discuss the link with (internal) crossed squares and pairs of compatible actions, and present some examples and applications....

##### Congruence modular variety and algebraic crystallography
2021-05-25
Speaker: Dominique Bourn (Université du Littoral, Calais, France)
See the attached file....

##### Uniform locales and their constructive aspects
2021-05-18
Speaker: Graham Manuell (CMUC)
Much work has been done on porting the theory of uniform spaces to the pointfree context and uniform frames/locales have proved to be a useful tool in this setting. However, much of the utility of the pointfree approach lies in its constructive theory. Formulating topological results...

##### A new diagonal separation and its relations with the Hausdorff property
2021-05-18
Speaker: Igor Arrieta (CMUC)
Let P be a property of subobjects relevant in a category C. An object X in C is P-separated if the diagonal in X × X has P; thus e.g. closedness in the category of topological spaces (resp. locales) induces the Hausdorff (resp. strong Hausdorff) axiom.In this talk we consider the...

##### A uniform action of the dihedral group Z_2 x D_3 on Littlewood-Richardson coefficients
2021-05-12
Speaker: Olga Azenhas (CMUC, Univ. Coimbra)
The Littlewood-Richardson (LR) coefficient symmetries under the action of the dihedral group $\mathbb Z_2\times D_3$ of order twelve refers to the invariance of LR coefficients, under an action of that group on LR triples of partitions, the partition-triples indexing LR...

##### Smooth representations of groups associated with algebras defined over non-archimedean fields
2021-04-28
Speaker: João Dias (CEAFEL, Univ. Lisboa)
In this talk, I will show a description of the irreducible smooth representations of algebra groups, unit groups of a split basic algebra and involutive algebra groups over a non-archimedean field (for example the p-adic field). In particular, I will discuss the admissibility and...

##### Bounded weak solutions to elliptic PDE with data in Orlicz spaces
2021-04-23
Speaker: David Cruz-Uribe (Univ. Alabama, USA)
See the attached file...

##### Feedback control of falling liquid films using a hierarchical model approach
2021-04-16
Speaker:

Susana Gomes (Univ. Warwick, UK)

The flow of a thin film down an inclined plane is a canonical setup in fluid mechanics and associated technologies, with applications such as coating, where the liquid-gas interface should ideally be flat, and heat or mass transfer, where an increase of interfacial area is desirable. In each...

##### Context-free word problem semigroups
2021-04-13
Speaker: Tara Brough (NOVA Univ. of Lisbon)

##### Algebraically cocomplete categories
2021-04-13
Speaker: Jiri Adámek (Technische Universität Braunschweig, Germany)
Dualizing the concept introduced by Freyd in 1990, a category is called algebraically cocomplete if every endofunctor has a terminal coalgebra. Among cocomplete categories these are just preordered classes. However, assuming the generalized continuum hypothesis (GCH), we present nice...

##### Jones polynomial, Khovanov homology and its geometrization
2021-04-09
Speaker: Marithania Silvero (Univ. Seville, Spain)
Knot Theory studies the classification of knots and links. Jones polynomial, introduced by Vaughan Jones in 1984, was one of the greatest breakthrough in this area, since it was the first polynomial knot invariant allowing to distinguish a knot from its mirror image. At the end of the past...

##### Entropy dissipation via Information Gamma calculus
2021-04-09
Speaker: Wuchen Li (Univ. South Carolina, USA)
In this talk, we present the convergence behavior for some non-gradient degenerate stochastic differential equations towards their invariant distributions in this talk. Our method extends the connection between Gamma calculus and Hessian operators in the L^2-Wasserstein space. In detail, we...

##### Minimal sets of generators
2021-03-23
Speaker: Alberto Facchini (Università di Padova, Italy)
A minimal set of generators of a right module MR over an associative ring R with identity is a subset X of M that generates M, but for any x∈ X, X∖{x} generates a proper submodule of MR. Unlike in the case of R a division ring, minimal sets of generators have little to do with...

##### Zariski-type spectra of localic ring-like structures
2021-03-23
Speaker: Graham Manuell (CMUC, Univ. Coimbra)
The Zariski spectrum provides a way to associate a locale to a commutative ring. Other spectrum constructions include the Stone spectrum of a distributive lattice and the prime spectrum of an MV-algebra. In many cases the algebraic structure comes equipped with a topology which must be taken...

##### Peg Problems
2021-03-17
Speaker: Joshua Greene (Boston College, USA)
Toeplitz asked in 1911 whether any Jordan curve in the Euclidean plane contains the vertices of a square. The problem remains open, but it has given rise to many interesting variations and partial results. I will discuss the proof of a related result which is best possible when the curve...

##### Besov-Morrey and Triebel-Lizorkin-Morrey spaces with variable exponents
2021-03-05
Speaker: António Caetano (Univ. Aveiro)
Our aim in this talk is to consider Besov-Morrey and Triebel-Lizorkin-Morrey spaces with variable exponents and present some of their properties, in particular the atomic and molecular representations. This reports on joint work with Alexandre Almeida (Besov-Morrey spaces) and Henning Kempka...

##### Colimits
2021-02-23
Speaker: Walter Tholen (York Univ., Toronto, Canada)
Extending Guitart's work of the 1970s, in this talk we eventually present the formation of the diagram category of a category and the formation of the Grothendieck category of a CAT-valued functor as adjoint 2-functors, and then establish a considerable generalization thereof. This...

2021-02-23
Speaker: Paolo Perrone (University of Oxford, UK)
Partial evaluations are a way to encode, in terms of monads, operations which have been computed only partially. For example, the sum "1+2+3+4" can be evaluated to "10", but also partially evaluated to "3+7", or to "6+4".Such structures can be defined...

##### The deformation cohomology of a symplectic groupoid
2021-02-17
Speaker: João Nuno Mestre (CMUC, Univ. Coimbra)
Symplectic groupoids are geometric objects that function as global counterparts to Poisson manifolds, in the same way that Lie groups are global counterparts to Lie algebras.In this talk I will first give an idea of how that analogy works, and I will present the construction of the...

##### Stochastic optimization of multiple objectives and fairness in machine learning
2021-02-12
Speaker: Luís Nunes Vicente (Lehigh Univ., USA & CMUC, Univ. Coimbra)
In the application of machine learning to real life decision-making systems, e.g., credit scoring and criminal justice, the prediction outcomes might discriminate against people with sensitive attributes, leading to unfairness. The commonly used strategy in fair machine learning is to...

##### Wallach spaces and Dirac operators
2021-01-20
Speaker: Ana Cristina Ferreira (CMAT, Univ. Minho)
Generalized Wallach spaces are homogeneous spaces of type III, sometimes also called tri-symmetric spaces in the literature. The 'original' Wallach spaces are those of positive sectional curvature and there exist only three of them in dimensions 6, 12 and 24. The three cases are related to...

##### On the 3x3x3-Lemma
2021-01-19
Speaker: Tim Van der Linden (UCLouvain, Belgium)
The idea of a short exact sequence of short exact sequences naturally leads to the 3x3-Lemma. What happens when this process is repeated? The aim of this talk is to explain the connection between the concept of a 3-fold extension, short exact sequences of 3x3-diagrams, and a congruence...

##### Abstract and concrete spectral spaces
2021-01-19
Speaker: George Janelidze (Univ. Cape Town, South Africa)
In this joint work with Alberto Facchini and Carmelo Antonio Finocchiaro we begin with a complete lattice L equipped with a binary multiplication such that the product of any two elements is less or equal to their meet. As suggested by the so-called "Abstract ideal theory" we...

##### Symbolic data and optimization
2021-01-15
Speaker:

Paula Amaral (NOVA Univ. of Lisbon)

Today, in many areas, we collect huge volumes of data to analyse. To use this data in classification methods it is necessary to aggregate them keeping as much information as possible about the data. Histograms are a useful way of representing large sets of data keeping...

##### Why I like noncommutative algebra: A tour of symmetry, geometry and mathematical physics
2021-01-15
Speaker: Samuel Lopes (CMUP, Univ. Porto)
I will start by motivating the study or noncommutative algebra and representation theory through examples rooted in symmetry, geometry and mathematical physics. Then I will talk about more specific aspects of my research interests....

##### Shifted Bender-Knuth moves and a shifted Berenstein-Kirillov group
2021-01-13
Speaker: Inês Rodrigues (CEAFEL, Univ. Lisboa)
The Bender-Knuth moves on Young tableaux are well-known involutions, namely, they are used in a combinatorial proof that the Schur functions are symmetric, as well as in alternative proofs of the classic Littlewood-Richardson rule. The group generated by these involutions, modulo the...

##### A new algorithm for the multiobjective minimum spanning tree
2021-01-07
Speaker: José Luís Santos (CMUC, Univ. Coimbra)
In this talk a new algorithm for the multiobjective minimum spanning tree problem is presented. It is based on a label algorithm for the multiobjective shortest path problem in a transformed network and can be used with any number of criteria. Some...

##### A new approach to S-protomodular categories
2021-01-05
Speaker: Tamar Janelidze-Gray (Univ. Cape Town, South Africa)
We propose a new approach to S-protomodular categories in the sense of D. Bourn, N. Martins-Ferreira, A. Montoli, and M. Sobral. Instead of points (=split epimorphisms) it uses generalized points, which we define as composable pairs of morphisms whose composites are pullback stable regular...

##### Relaxed actions of monoids: Towards a new cohomology theory
2021-01-05
Speaker: Peter Faul (University of Cambridge, UK)
Artin glueings between frames have much in common with semidirect products of groups. If H and N are groups (frames) then the process of constructing semidirect products (Artin glueings) provides a means of finding all objects in which N embeds as a normal (closed) subobject and H embeds as...

##### The s-numbers, eigenvalues and generalized trigonometric functions
2020-12-18
Speaker: Jan Lang (Ohio State Univ., USA)
Generalized trigonometric functions, which were first introduced by Lundberg 1879, will be discussed together with their connections with p-Laplacian, approximation theory and s-numbers for Sobolev embedding. ...

##### Sharp inequalities for the Ornstein-Uhlenbeck operator
2020-12-11
Speaker: Lubos Pick (Charles Univ., Prague, Czechia)
The abstract is attached....

##### Model-based evaluation of school- and non-school based public health measures on controlling the COVID-19 pandemic in the Netherlands
2020-12-11
Speaker: Ganna Rozhnova (University Medical Center Utrecht, Netherlands)
Introduction: In autumn 2020, many countries, including the Netherlands, are experiencing a second wave of the COVID-19 pandemic. Health policymakers are struggling with choosing the right mix of measures to keep the COVID-19 case numbers under control, but still allow a minimum of social...

##### Commutation classes of the reduced words for the longest element of the symmetric group
2020-12-10
Speaker: Ricardo Mamede (CMUC, Univ. Coimbra)
Using the standard Coxeter presentation for the symmetric group, two reduced expressions for the same group element w are said to be commutationally equivalent if one expression can be obtained from the other one  by applying a finite sequence of commutations. The commutation...

##### Quasihereditary algebras with exact Borel subalgebras
2020-12-09
Speaker: Teresa Conde (Univ. Stuttgart, Germany)
Exact Borel subalgebras of quasihereditary algebras emulate the role of "classic" Borel subalgebras of complex semisimple Lie algebras. Not every quasihereditary algebra A has an exact Borel subalgebra. However, a theorem by Koenig, Külshammer and Ovsienko establishes that...

##### Characterizations of normality given by C-, C^*- and z-embedded sublocales
2020-12-02
Speaker: Ana Belén Avilez (PhD student, CMUC)

##### Sublocales as parts
2020-12-02
Speaker: Imanol Mozo Carollo (Univ. of the Basque Country, Bilbao, Spain)

##### Laws of rare events for chaotic dynamics
2020-12-02
Speaker: Ana Cristina Moreira de Freitas (CMUP, Univ. Porto)
The extremal index appears as a parameter in Extreme Value Laws, characterising the clustering of extreme events. We apply this idea to a dynamical systems context to analyse the possible extreme value laws for the stochastic process generated by observations taken along dynamical orbits....

##### Strong solutions of parabolic equations with p(x,t)-Laplacian: existence and the global regularity properties
2020-11-27
Speaker: Sergey Shmarev (Univ. Oviedo, Spain)
TBA...

##### The Schroedinger problem
2020-11-26
Speaker: Dmitry Vorotnikov (CMUC, Univ. Coimbra)
Schroedinger’s hot gas experiment aimed for determining the most likely evolution between two subsequent observations of a cloud of particles. Seemingly purely stochastic, this problem can be translated into a geometric language. Given a fixed functional on a Riemannian...

##### Complex network of epidemic models
2020-11-20
Speaker:

Cristiana J. Silva (CIDMA, Univ. Aveiro)

In this work, we consider an epidemiological model given by a system of ordinary equations, for the transmission dynamics of SARS-CoV-2, with piecewise constant parameters. Based on this model, we construct a complex network of dynamical systems, in order to take into account the...

##### Statistical stability in chaotic systems (CANCELLED)
2020-11-19
Speaker:

José Ferreira Alves (CMUP, Univ. Porto)

We will make a brief introduction to the theory of dynamical systems, focusing our attention on the class of chaotic systems. We will pay special attention to the Lorenz attractor, well known for the "butterfly effect". We will see that, despite the impossibility of predicting...

##### On the combinatorics of linear dependencies of 0-1 vectors
2020-11-18
Speaker: Ilda Perez Fernandez Silva (Univ. Lisboa)
It was recently proven (J. Geelen, B. Gerards, G. Whittle) that linear dependence over any given finite field can be characterized combinatorically, via matroids, in terms of a finite number of excluded subconfigurations (minors). It is known that representability over the reals can not be...

##### Link invariants from finite crossed modules and a lifting of the Eisermann invariant
2020-11-16
Speaker: Roger Picken (IST, Univ. Lisbon)
This talk is based on work with João Faria Martins (Univ. Leeds) [1] and several projects with students. I will describe the construction of an invariant of tangles and framed tangles which takes values in an arbitrary crossed module of finite groups. This involves the fundamental...

##### Training reaction diffusion models for image restoration
2020-11-12
Speaker: Sílvia Barbeiro (CMUC, Univ. Coimbra)
Image restoration is one of the major concerns in image processing with many interesting applications. In the last decades there has been intensive research around the topic and hence new approaches are constantly emerging. Partial differential equation (PDE) based models, namely of...

##### Finite fields meet Markov chains
2020-11-11
Speaker: Persi Diaconis (Stanford Univ., USA)
In joint work with Jimmy He and Marty Isaacs we have been exploring a curious interface between Galois theory and Probability. The problems are easy to state: Consider first Z/pZ. A random walk takes x to x+1 or x-1 with probability 1/2. As I will explain, it takes order p^2 steps (N&S)...

##### Characterization of coextensive varieties of universal algebras
2020-11-10
Speaker: David Neal Broodryk (University of Cape Town, South Africa)
A coextensive category can be defined as a category C with finite products such that for each pair X,Y of objects in C, the canonical functor ×:X/C×Y/C→(X×Y)/C is an equivalence. This is the dual of an extensive category, a term that was first used by W. F. Lawvere and...

##### Pretorsion theories and internal preorders
2020-11-10
Speaker: Marino Gran (UCLouvain, Belgium)

##### Mathematical modelling in solid mechanics: an example with fracking
2020-11-06
Speaker: Nicolas Van Goethem (CMAFCIO, Univ. Lisboa)
I will present the various steps of mathematical modelling on a practical case: presentation and setting of the problem (hydraulic fracture), choice of the approach (energergetical and variational), choice of the method (topological differentiation), design of the algorithm (quasi-static and...

2020-11-06
Speaker: Rafayel Teymurazyan (CMUC)
We study fully nonlinear dead-core systems coupled with strong absorption terms. We discover a chain reaction, exploiting properties of an equation along the system. The lack of both the classical Perron's method and comparison principle for the systems requires new tools for tackling the...

##### Unfolding a Bykov attractor: from an attracting torus to strange attractors
2020-11-05
Speaker: Alexandre Rodrigues (CMUP, Univ. Porto)
We present a comprehensive mechanism for the emergence of strange attractors in a two-parametric family of differential equations acting on a three-dimensional sphere. When both parameters are zero, its flow exhibits an attracting heteroclinic network (Bykov network) made by two...

##### Geometry and Topology of Higgs bundles moduli spaces
2020-10-29
Speaker: André Oliveira (CMUP, Univ. Porto)
A Higgs bundle over a Riemann surface is a pair consisting of a vector bundle together with some extra data. Their moduli spaces are quasi-projective varieties which naturally appear in many different areas of Mathematics and even of Physics. In this talk, we will take a general overview...

##### An introduction to combinatorial commutative algebra
2020-10-22
Speaker: Jorge Neves (CMUC, Univ. Coimbra)
Combinatorial Commutative Algebra comes of age following the works of Richard Stanley in the late seventies of the last century. A typical research problem consists of associating an ideal (or ring) to a given type of structure (simplicial complexes, graphs, polytopes, matroids, etc.) and to...

##### On orthogonal polynomials and their applications
2020-10-15
Speaker: José Carlos Petronilho (CMUC, University of Coimbra)
In this talk we will give an overview of the theory of orthogonal polynomials (OP), focusing on the so-called inverse problems. The problems to be considered arise in the framework of Sobolev OP and the theory of polynomial mappings. We will point out several applications, including...

##### The theory of exactness properties: recent developments and work in progress
2020-10-13
Speaker: Zurab Janelidze (Stellenbosch University, South Africa)
By the "theory of exactness properties" we mean a subject that is in similar relation to the theories of semi-abelian categories, abelian categories, etc., as universal algebra is to group theory, module theory, etc. These classes of categories (semi-abelian, abelian, etc.) are...

##### Variations on distributive laws
2020-10-13
Speaker: Nicola Gambino (University of Leeds, UK)
The notion of a distributive law between monads goes back to fundamental work of Jon Beck from the late ‘60s. Just as a monad describes a kind of algebraic structure, a distributive law between two monads describes how the algebraic structure for one monad distributes over the...

##### Mathematical models and methods for Breach Formation in Earth Embankment Dams
2020-09-16
Speaker: Giuseppe Romanazzi (Unicamp, Campinas, Brazil)
After an overview of breach formation in embankment dams, we present different mathematical models and methods used nowadays to predict the formation of breach in earth embankments. The strengths and weaknesses of the prediction models are discussed....

##### The Karoubi envelope of the mirage of a subshift
2020-09-15
Speaker: Alfredo Costa (CMUC, Univ. Coimbra)
Free profinite semigroups are completions of free semigroups, and for that reason their elements are frequently called pseudowords. Around 2003, Almeida introduced a fruitful connection between symbolic dynamical systems (also known as subshifts) and free profinite semigroups. Following...

##### The polycyclic inverse monoids and the Thompson groups revisited
2020-09-15
Speaker: Mark Lawson (Heriot-Watt University, UK)

##### Discrete covers of locales
2020-07-14
Speaker: Igor Arrieta Torres (PhD Student, CMUC)
See attached file....

##### Some fibrational properties of normal monomorphisms
2020-07-14
Speaker: Giuseppe Metere (Universitá degli Studi di Palermo, Italy)
Several classes of monomorphisms have been introduced in general algebraic contexts. For some of them, there is a purely categorical description that makes it possible a formal study of their structure. In my talk, after a quick recap of such notions, I will focus on the normal subobjects in...

##### Cactus group actions on shifted tableau crystals and a shifted Berenstein-Kirillov group
2020-07-01
Speaker: Inês Rodrigues (CEAFEL, Univ. Lisboa)
Recently, Gillespie, Levinson and Purbhoo introduced a crystal-like structure for shifted tableaux, called the shifted tableau crystal. We introduce a shifted version of the crystal reflection operators, which coincide with the restrictions of the shifted Schützenberger involution to...

##### Tensors of KZ-algebras
2020-06-30
Speaker: Marcelo Fiore (University of Cambridge, UK)
We investigate tensors of pseudo-algebras for KZ (aka lax idempotent) 2-monads. Our leading example is the tensor product of (unsorted) algebraic theories. This will be used throughout the talk to motivate and present the abstract theory.We shall consider tensors both in the sense of...

##### Characterizations of lax orthogonal factorization systems
2020-06-30
Speaker: Charles Walker (Masaryk University, Czech Republic)
See attached file....

##### Intrinsic Schreier split extensions and intrinsic Schreier special objects
2020-06-02
Speaker: Andrea Montoli (Univ. degli Studi di Milano, Italy)
We explore, in the context of regular unital categories with comonadic projective covers, intrinsic notions of Schreier split epimorphisms and Schreier special objects. These intrinsic notions allow, on one hand, to understand categorically the properties of Schreier split extensions of...

##### Double categories of open dynamical systems
2020-06-02
Speaker: David Jaz Myers (Johns Hopkins University, USA)
A dynamical system consists of a notion of how things may be, and a notion of how things may change, given how they are. There are many sorts of dynamical systems --- discrete, continuous, probabilistic, non-deterministic --- and the dynamics often depend on parameters which themselves may...

##### A non-Levi branching rule in terms of Littelmann paths
2020-05-20
Speaker: Jacinta Perez Gavilan Torres (Institute of Mathematics, Polish Academy of Sciences)
We will give an introduction to the Littelmann path model for representations of simple Lie algebras, highlighting its most important applications and connectionsto algebraic combinatorics. Then we will present a non-Levi branching rule in terms of Littelmann paths. This is joint work with...

##### From preordered groups to quantale-enriched groups
2020-05-05
Speaker: Maria Manuel Clementino (CMUC, Univ. Coimbra)
Based on the study of preordered groups of [1], we introduce and study V-groups and their homomorphisms, for a commutative and unital quantale V.(This talk is based on joint work with Andrea Montoli [2].) References:[1] M.M. Clementino, N. Martins-Ferreira, A. Montoli, On the...

##### Actions of preordered monoids and their associated extensions
2020-05-05
Speaker: Nelson Martins-Ferreira (IP Leiria, CDRSP)
The category of preordered monoids can be seen either as a category of internal preorders in monoids or as the category of internal monoids in preorders. In this talk, we start by analysing differences and similarities between preordered groups and preordered monoids. In particular, we study...

##### Sharp concentration estimates near criticality for sign-changing solutions of Dirichlet and Neumann problems
2020-02-28
Speaker: Hugo Tavares (IST, Univ. Lisboa)
Consider the slightly subcritical problem $-\Delta u_\varepsilon = |u_\varepsilon|^{\frac{4}{n-2}-\varepsilon}u_\varepsilon$ either on $\mathbb{R}^n$ ($n\geq 3$) or in a ball $B$ satisfying Dirichlet or Neumann boundary conditions. For radial solutions, we provide sharp rates and constants...

##### Is fractional calculus the ultimate solution to all anomalous-diffusion problems?
2020-02-28
Speaker: Luís Ferrás (Univ. do Minho)
Albert Einstein, in his work regarding Brownian motion (1905) entitled "On the motion of small particles suspended in liquids at rest required by the molecular-kinetic theory of heat", gave the definitive confirmation that atoms and molecules exist. Since then, many works have...

##### Revisiting the relation between subspaces and sublocales
2020-02-18
Speaker: Anna Laura Suarez (Univ. Birmingham, UK)
One of the main features distinguishing pointfree topology from classical point-set one is that in the pointfree setting a space (i.e. a locale) may have abstract subspaces (sublocales) which do not have any point-set analogue. The lattice of sublocales of a locale will not in general be a...

##### Enriched Priestley spaces
2020-02-18
Speaker: Dirk Hofmann (Univ. Aveiro)
See attached file....

##### Optimization meets Medical Physics: tailored algorithms
2020-02-14
Speaker: Humberto Rocha (School of Economics, Univ. Coimbra)
Radiotherapy has been a fertile field for the development of algorithms to tackle the different optimization problems that arise in this area. A panoply of algorithms has been used for different problems including integer programming, linear programming or quadratic programming algorithms....

##### Sweeping processes and evolution problems with bounded variation
2020-02-14
Speaker: Manuel Monteiro Marques (Univ. Lisboa)
Evolution problems governed by maximal monotone operators with domains that depend on time are present in many areas.The special case of the sweeping process, where the operators are normal cones to time-dependent convex moving sets, was treated by Jean Jacques Moreau in the seventies,...

##### On q-polynomials: some old and new results
2020-02-07
Speaker: Renato Álvarez-Nodarse (Univ. Sevilla, Spain)
The first family of q-polynomials appears in the works of Stieltjes and at the end of the XIX century, and have been attracted great interest since then. They are related with a lot of pure mathematical problems but also with applied ones. In this talk I will try to give an idea of the...

##### On difunctionality of class relations
2020-01-31
Speaker: Diana Rodelo (CMUC and Univ. Algarve)
See attached file....

##### Categorical aspects of congruence distributivity
2020-01-31
Speaker: Idriss Tchoffo Nguefeu (UCLouvain, Belgium)
We give new characterisations of regular Mal'tsev categories with distributive lattice of equivalence relations through variations of the so-called Triangular Lemma and Trapezoid Lemma in universal algebra. We then give new characterisations of equivalence distributive Goursat categories...

##### Mirror symmetry on the Hitchin system
2020-01-24
Speaker: Emilio Franco Gomez (CAMGSD, IST, Lisboa)
We will provide an overview of Mirror Symmetry phenomena occurring in the framework of the Hitchin system....

##### Branes on the Hitchin system via torsion bundles
2020-01-24
Speaker: André Oliveira (CMUP & UTAD)
We study the fixed point loci on the moduli space M of GL(n,C)-Higgs bundles (over a curve) for the action of tensorization by a torsion line bundle of order n. This is a hyperholomorphic loci which can be equipped with a hyperholomorphic sheaf, hence is constitutes a BBB-brane on M. Such a...

##### The feasible region for consecutive occurrences of large permutations
2020-01-22
Speaker: Raúl Penaguião (Univ. Zürich, Switzerland)
The study of patterns in permutations has steadily gathered interest in combinatorics. The notion of classical pattern has been well studied so far, for instance giving rise to the limit object of a permuton. The proportions of these patterns takes values between zero and one and the precise...

##### Proposition 15 in Euclid's Optics
2020-01-15
Speaker: Daniel M. Pinto (CMUC, Univ. Coimbra)
One of the oldest and, despite its flaws, most important books in geometric optics is, undoubtely, Euclid's Optics. We will take a close look at some versions and translations of the original book, paying special attention to the proof of Proposition 15....

##### Combinatorics and moduli of line bundles on stable curves
2020-01-15
Speaker: Ana Margarida Melo (CMUC, Univ. Coimbra)
The moduli space of line bundles on smooth curves of given genus, the so called universal Jacobian, has a number of different compactifications over the moduli space of stable curves. These compactificatons have very interesting combinatorial properties, which can be used to describe their...

##### The Method of Fundamental Solutions and its application for solving shape optimization problems
2020-01-10
Speaker: Pedro Antunes (Univ. Aberta, Lisboa)
This talk is divided into two parts. In the first part we give an overview of the application of the Method of Fundamental Solutions (MFS) for solving boundary value problems with elliptic PDE's. The MFS is a meshfree method where the solution is approximated by a linear combination of...

##### A walk from D-modules to distribution theory through the conjugation functor
2020-01-08
Speaker: Teresa Monteiro Fernandes (CMAFcIO, Univ. Lisboa)
I will recall Kashiwara's conjugation functor from the derived category of regular holonomic D-modules over a complex manifold to the derived category of regular holonomic D-modules on the complex conjugate manifold \bar{X}, which he proved to be an equivalence of categories thanks to the...

##### Quantum matrix algebras: a review
2020-01-06
Speaker: Dmitry Gurevich (Valenciennes Univ., France)
I plan to define certain well-known and new quantum matrix algebras (for instance, Generalized Yangians) and discuss their properties.In particular, I'll consider the problem of defining quantum determinants and other symmetric polynomials in all of them. Also, I'll exhibit some...

##### Information in additional observations from a non-parametric experiment
2019-12-18
Speaker: Tilo Wiklund (Univ. of Uppsala, Sweden)
Given some statistical experiment E we may, at least in principle, make multiple, independent, repetitions of it. Say that one statistician repeats the experiment n times, while another repeats it n+1 times. How much better off will the latter be? They certainly should not do be any worse...

##### Specht modules for general diagrams, their Schur functions, and Mondrian tableaux
2019-12-18
Speaker: Olga Azenhas (CMUC, Univ. Coimbra)
The question of how to decompose a Specht module, for an arbitary diagram, into irreducible submodules, is not yet known. Similar question for Schur functions for arbitrary diagrams. We discuss known results for skew shapes, in particular, border strips, or forests, and the role of R. Liu's...

##### Finitely presentable algebras for finitary monads
2019-12-17
Speaker: Lurdes Sousa (CMUC and IP Viseu)
A variety of algebras is nothing else than the category of algebras of a finitary monad on Set, and, in this case, an algebra A is finitely presentable if it can be presented by a finite set of generators and a finite set of equations. We generalize this to finitary regular monads on...

##### Matrix functions: applications, computation and topics of research
2019-12-11
Speaker: João Cardoso (ISEC & CMUC)
The first known references to matrix functions can be found in the works of Cayley, Laguerre, Peano and Sylvester in the second half of the 19th century.  However, just in the last decades of the 20th century we assisted to a growing interest in developing methods for the computation of...

##### Maths for crime prediction
2019-12-11
Speaker: Adérito Araújo (CMUC, Univ. Coimbra)
It is undeniable that an unfortunate aspect of modern life, technologically and economically more developed, is the presence of crime distributed in major urban areas. This does not only affect countries like Portugal or the European continent, but is experienced in all countries around the...

##### Multiobjective optimization: fundamentals and an application in demand response
2019-12-04
Speaker: Maria João Alves (Faculty of Economics, Univ. Coimbra)
In this talk, the fundamental concepts of multiobjective optimization and scalarizing techniques to compute nondominated solutions will be introduced. Scalarizing techniques consist of transforming the original multiobjective problem into a single objective problem that may be solved...

##### The moduli spaces of Higgs bundles
2019-12-02
Speaker: André Oliveira (CMUP)
Given a Lie group G, the notion of G-Higgs bundle on a compact Riemann surface was introduced in the 1980s and 1990s by Nigel Hitchin. The algebraic varieties that parameterize these objects, i.e. their moduli spaces, have an extremely rich geometric and topological structure, yet are far...

##### Emergence of strange attractors from singularities
2019-11-27
Speaker: Alexandre Rodrigues (CMUP, FCUP)
In this seminar, we explore some mechanisms to obtain strange attractors (with one or two positive Lyapunov exponents). We will discuss some open questions related to the existence of strange attractors near a special type of homoclinic cycle (associated to a bifocus). This seminar is...

##### A two-phase free boundary problem ruled by the infinity laplacian
2019-11-22
Speaker: Damião Araújo (Universidade Federal da Paraíba, Brazil)
In this talk we discuss regularity aspects for solutions of a non-variational two-phase free boundary problem ruled by the infinity Laplacian. This is a joint work with E. Teixeira - University of Central Florida - USA and J.M Urbano - Universidade de Coimbra - PT....

##### Stone pseudovarieties
2019-11-19
Speaker: Jorge Almeida (CMUP, Univ. Porto)
Profinite algebras have been extensively considered in the literature, particularly in the realms of groups and semigroups. They are the residually finite topological algebras over Stone spaces. In this talk, we consider classes of Stone topological algebras of a fixed signature that are...

##### Split extensions of monoids and Hopf algebras
2019-11-19
Speaker: Florence Sterck (Université catholique de Louvain, Belgium)
In the category of groups, split extensions have a lot of interesting properties. One of them is the fact that the category of split extensions is equivalent to the category of group actions.Unfortunately, this property doesn't hold in the category of monoids. Nevertheless, it was proved in...

##### Thermodynamic formalism of non-uniformy expanding maps
2019-11-13
Speaker: Paulo Varandas (UFBA & Univ. Porto)
Ergodic theory is the branch of dynamical systems which aims to describe the asymptotic behavior of almost all orbits, with respect to invariant measures.  However there are situations in which such a description is rather trivial, as the case when the invariant measures are finite...

##### A generalized approach to stochastic dominance
2019-11-13
Speaker: Tommaso Lando (Univ. of Bergamo, Italy & VSB-TU Ostrava, Czech Republic)
In the theory of decision under uncertainty, ranking probability distributions with respect to the preferences of decision makers represents a major issue. In this context, the main ranking criteria are the first and the second-order stochastic dominance, FSD and SSD, respectively, due to...

##### Corruption cycles in democracy
2019-11-13
In this talk, with the goal of analysing the evolution of corruption, we introduce an evolutionary game theoretic dynamical model describing the interaction of citizens with government and officials or bureaucrats of the state in a democratic country.We study and interpret the...

##### Dynamical systems from mutation-periodic quivers: definition and reduction by pre-symplectic tools
2019-11-06
Speaker: Inês Cruz (CMUP, FCUP)
Cluster algebras and their associated quivers were introduced in 2002 by Fomin and Zelevinsky to provide a framework to study total positivity in matrix groups. Since then, cluster algebras have been successfully linked to a wide range of subjects including Poisson geometry, integrable...

##### Some challenging problems on numerical semigroups
2019-10-30
Speaker: Manuel Delgado (CMUP, Univ. Porto)
A numerical semigroup is just a co-finite submonoid of the nonnegative integers, under addition. Despite being so simple mathematical objects, they hide very challenging combinatorial and computational problems (among others, coming from various areas of mathematics). The aim of the seminar...

##### Differential equations with two time-scales
2019-10-30
Speaker: Isabel Labouriau (CMUP, Univ. Porto)
I'll discuss the role of different time-scales in differential equations and the associated geometry. This will be illustrated by a simple example, the FitzHugh-Nagumo equations, and by two of these equations coupled to form a system in ${\mathbb R}^4$. When two different time-scales are...

##### Novel applications of approximation theory to diverse problems in random matrices
2019-10-25
Speaker: Nicholas Witte (Univ. Massey, New Zealand)
We take three contemporary problems arising from random matrices and show how approximation theory is crucial in solving them. However this is not merely an "off-the-shelf" application of known results from within approximation theory, but require extensions beyond the realm of its...

##### The prevalence of persistent tangles
2019-10-23
Speaker: Pedro Lopes (IST, Univ. Lisboa)
This talk addresses persistent tangles. These are tangles whose presence in a knot diagram forces that diagram to be knotted. We provide newmethods for constructing persistent tangles. Our techniques rely mainly on the existence of non-trivial colorings for the tangles in question. Our main...

##### Frankl Conjecture
2019-10-23
Speaker: André Carvalho (UC|UP PhD student)
This seminar will deal with a conjecture proposed in 1979 by Peter Frankl related to union-closed families of sets. Despite the fact that the conjecture regards finite union-closed families of sets, which appear to be very simple objects, very little is known about them. We try to present in...

##### Categorical semantics of intuitionistic linear logic
2019-10-23
Speaker: Carlos Fitas (UC|UP PhD student)
The Curry-Howard-Lambek correspondence shows the deep connection between programs, proofs and morphisms in closed cartesian categories. It's natural to ask if similar results are true in other logics. Identifying the intuitionistic linear logic derivations up to the transformations in cut...

##### On entropy functionals associated with Bernstein stochastic processes
2019-10-18
Speaker: Pierre Viullermot (Univ. Lorraine & Univ. Lisboa)
Bernstein processes constitute a generalization of Markov processes, and there are many equivalent ways to define them. In this talk I will show how to generate such processes from a hierarchy of forward-backward systems of decoupled deterministic linear parabolic partial differential...

##### An ageing ordering
2019-10-16
Speaker: Beatriz Santos (UC|UP PhD student)
Many classes of lifetime distributions are characterized by their ageing properties, that can be described by their survival functions or by their failure rate functions. These ageing properties allow us to compare two distributions within the same family, giving rise to ageing orderings....

##### Ergodic theorems from topological and probabilistic viewpoints
2019-10-16
Speaker: Lucas Amorim (UC|UP PhD student)
Ergodic theorems are classic measure theoretical results in dynamical systems or, more precisely, ergodic theory. They state that convergence of Birkhoff averages is typical, in a measure theoretical sense. This work aims to explain how these results can be reìnterpreted in light of...

##### The Picard group of the universal G-bundle over the moduli stack of pointed curves
2019-10-16
Speaker: Filippo Viviani (CMUC/Roma Tre)
I will report on a joint work (in progress) with R. Fringuelli where we compute the Picard group of the moduli stack parametrizing pairs consisting of a smooth pointed curve C together with a G-principal bundleon C, for a given reductive algebraic group G....

##### Functorial semantics and descent II
2019-10-15
Speaker: Fernando Lucatelli Nunes (CMUC, Univ. Coimbra)
Restricting our attention to the 2-category of categories, the main result of [1] gives in particular a natural factorization of functors via descent. Moreover, under suitable hypothesis, this factorization is shown to coincide with the semantic factorization of the functor. This gives as a...

##### Injectives via actions or: How I learned to stop worrying and love quantales
2019-10-15
Speaker: Eros Martinelli (CIDMA, Univ. Aveiro)
In this talk, motivated by a classical result that relates injectives V-categories with injectives (= complete) ordered sets with an action, we prove a similar result for (L,V)-categories where L is the list monad....

##### Deep learning meets PDEs: an effective framework for image restoration
2019-10-09
Speaker: Sílvia Barbeiro (CMUC, Univ. Coimbra)
Image restoration is one of the major concerns in image processing with many interesting applications. Partial differential equation (PDE) based models, namely of nonlinear diffusion type, are well-known and widely used for image noise removal. In this seminar we will describe a flexible...

##### Algebras associated to quivers
2019-10-02
Speaker: Rui Prezado (UC|UP PhD student)
Given a small category I, its representation theory is, in essence, the study of the functor category [I,R-Mod] for some (not necessarily commutative) ring R. A case of interest is when we have I freely generated by a quiver Q. We construct an R-algebra RQ associated to this quiver Q in two...

##### Spectral analysis in the study of dynamical systems
2019-10-02
Speaker: Raquel Couto (UC|UP PhD student)
After a brief journey into a class of Symbolic Dynamical Systems, that is related to Markov Chains, I will present the Limit Theorem for Markov Chains which can be obtained as a corollary of Perron Theorem (a spectral theorem in linear algebra). Next, we will see what may be taken as a...

##### Coupled cell networks and systems
2019-09-25
Speaker: Ana Paula Dias (CMUP)
The aim of this talk is to introduce the connection between coupled cell networks and coupled cell systems. We also plan to address the issue of classifying networks from the dynamics point of view.  The seminar takes place in PORTO....

##### On nilpotent elements
2019-09-18
Speaker: Miguel Gómez Lozano (Univ. Málaga, Spain)
See the attached file....

2019-07-18
Speaker: M. Redivo-Zaglia (Univ. degli Studi di Padova, Italy)
We consider a particular case of the general rational Hermite interpolation problem where the value of a function f is interpolated at some points, and where the formal series expansions at the origin of the rational interpolant and of f agree as far as...

##### The homotopy type of shifted cotangent bundles
2019-07-12
Speaker: Ricardo Campos (Univ. Montpellier, France)
Given a vector bundle E over a smooth manifold M, the algebra of functions on its shifted cotangent bundle T*[1]E has a natural structure of a Lie algebra and solutions of the Maurer-Cartan equation correspond to Lie algebroid structures on E. Allowing E to be a dg bundle (bundle of chain...

##### The Schützenberger involution on Kashiwara-Nakashima tableaux
2019-06-26
Speaker: João Miguel Santos (CMUC, Univ. Coimbra)
The Schützenberger involution, due to Schützenberger, originally appeared in type A root system, using the model of semistandard Young tableaux. In this talk, we present a type C realization of the Schützenberger involution using the model of Kashiwara-Nakashima tableaux....

##### Algebraic and geometric classification of nilpotent Tortkara algebras
2019-06-12
Speaker: Mykola Khrypchenko (Univ. Federal de Santa Catarina, Brazil)
We classify all nilpotent Tortkara algebras of dimension 6 over the field of complex numbers. We also determine the rigid algebras and irreducible components of the variety of such algebras. This is a joint work with Ilya Gorshkov (Sobolev Institute of Mathematics) and Ivan Kaygorodov...

##### Parametric Presburger arithmetic
2019-06-12
Speaker: Tristram Bogart (Univ. de los Andes, Colombia)
Parametric Presburger arithmetic concerns families of sets defined using quantifiers and Boolean combinations of formulas of the form a(t)·x ≤ b(t), where a(t) ∈ Z[t] d , b(t) ∈ Z[t]. In the quantifier-free these formulas represent sets of integer points in families of...

##### The geometry of generalized flat ribbons
2019-06-12
Speaker: Matteo Raffaelli (CMUC)
In this talk we will be studying the problem of approximating -- locally along a curve -- a given surface S in three-space by a developable (i.e., flat) one. Naturally, we will consider tangent approximations, where the approximating strip-shaped surface, or ribbon, has the same distribution...

##### Normally ordered forms of powers of differential operators
2019-06-05
Speaker: Samuel Lopes (CMUP, Univ. Porto)
See the attached file....

##### Sequence Morrey space and Pitt's type theorem
2019-05-31
Speaker:

Leszek Skrzypczak (Adam Mickiewicz Univ., Poznan, Poland)

Morrey (function) spaces and, in particular, smoothness spaces of Besov-Morrey or Triebel-Lizorkin-Morrey type enjoyed a lot of interest recently. Here we turn our attention to Morrey sequence spaces mu,p =mu,p(Zd), 0<p\leq u<\infty, which have yet been considered almost nowhere. They...

##### On the dimension formula for Goldie's uniform dimension
2019-05-29
Speaker: Christian Lomp (Univ. Porto)
A classical (right) ring of fractions of a ring R is an overring Q(R) of R such that any non-zero divisor of R is invertible in Q(R) and any element of Q(R) is of the form ab^{-1} for a and b elements of R with b a non-zero divisor. Oystein Ore proved in the 30s that a (non-commutative)...

##### Introduction to causal analysis
2019-05-29
Speaker: Maria Králová (Masaryk Univ., Czech Republic)
Researchers in many areas where only observational data are available often face the challenge of assessing the effect of the treatment on the outcome.  Within a framework of traditional statistical analysis of multivariate data, only different measures of association are available....

##### Regularity for elliptic equations under minimal assumptions
2019-05-24
Speaker: Giuseppe Di Fazio (Università di Catania, Italy)
Elliptic PDEs are ubiquitous in Mathematics and Sciences. A very important topic concerning elliptic PDEs is the regularity of solutions. We will review some regularity results for linear and quasilinear uniformly elliptic equations. The main focus will be on the minimal assumptions we need...

##### Recent thoughts about the NIEP
2019-05-15
Speaker: Charles Johnson (College of William and Mary, Williamsburg, USA)
We discuss 3 topics about the nonnegative inverse eigenvalue problem about which recent progress has been made. These include 1) ruling out certain spectra for the 5-by-5 S-NIEP; 2) Jordan structure for realizable spectra with repeated eigenvalues; and 3) the doubly stochastic single...

##### Feedback invariants of series connected systems and LR coefficients
2019-05-15
Speaker: Marija Dodig (Univ. Lisboa)
In this talk we shall describe the possible feedback invariants of linear systems obtained as a result of series connections of two linear systems. This corresponds to a completion problem for matrices. We solve the problem in a generic case, and we conjecture general solution. It turns...

##### Spin-orbit coupling in the Solar System
2019-04-24
Speaker: Alexandre C. M. Correia (DFUC, Univ. Coimbra)
Recent developments in the study of the Solar System dynamics have shown that it is not such a quiet place. Mutual interactions between all bodies may destabilise the orbits and the spins of all terrestrial planets and satellites. Chaotic motion is everywhere and our present quiet Earth will...

##### Lagrangian systems with external forces preserving geometric structure
2019-04-24
Speaker: David Martin de Diego (ICMAT, Madrid, Spain)
In this talk we will discuss the geometric description of mechanical systems with external forces. Some of these systems has additional geometric features and we will study if it is possible to preserve some of these properties using geometric integrators like variational integrators...

##### Colimit-dense subcategories
2019-04-23
Speaker: Jiří Adámek (Tech. Univ. Braunschweig, Germany)
A small full subcategory K' of a category K is called dense (or colimit-dense) if every object X of K is a colimit of some diagram in K' (or is the canonical colimit of all maps from objects of K' to X, resp.). The existence of a colimit-dense subcategory is an important property, e.g., the...

##### Crossed semimodules of cancellative conjugation monoids
2019-04-23
Speaker: Nelson Martins Ferreira (CDRSP, ESTG, IP Leiria)
This talk is based on the work [1] where we show that the category of cancellative conjugation semigroups is weakly Mal'tsev and give a characterization of all admissible diagrams there.In the category of cancellative conjugation monoids we describe, for Schreier split epimorphisms with...

##### Dynamics, symmetry and patterns: a tour of Einstein, Ginzburg and Landau
2019-04-12
Speaker: Phillipo Lappicy (USP, Brazil, and IST, Lisbon)
This talk will present my recent results in certain directions within the realm of partial differential equations. On one hand, parabolic equations generate a semiflow in infinite dimensions, and hence we are interested in the dynamical question: what happens when time is large? We will...

##### Rees algebras of modules
2019-04-10
Speaker: Ana Luísa Correia (Academia Militar and CEAFEL - FCUL)
The Rees algebra of an ideal may be seen as a coordinate ring of a projective variety and it plays an important role in the study of algebraic singularities. Many parts of this theory can also be extended to the case of filtrations ideals or modules, as well to the case of the multi-Rees...

##### Describing the singular behaviour of parabolic equations on cones in fractional Sobolev spaces
2019-04-05
Speaker: Cornelia Schneider (Univ. Erlangen-Nuremberg, Germany)
This talk focusses on the smoothness of the solutions of parabolic PDEs on Lipschitz domains in the fractional Sobolev scale Hs, s in R. The regularity in these spaces is related with the approximation order that can be achieved by numerical schemes based on uniform grid refinements. The...

##### Geometric constructions: some working hypotheses
2019-04-02
Speaker: Graziani Pierluigi (Univ. of Urbino Carlo Bo, Italy)
Among the many theses regarding the nature of Greek mathematics, the most popular one held by historians and philosophers of ancient mathematics is that Greek mathematics, in particular Euclid's Elements, has a constructive nature. However, it is not always clear what the defenders of this...

##### Peregrine's system revisited
2019-03-27
Speaker: Ángel Durán (Univ. Valladolid, Spain)
In 1967, D. H. Peregrine proposed a Boussinesq-type model for long waves in shallow waters of varying depth (Peregrine, J Fluid Mech 27:815-827, 1967). This prominent paper turned a new leaf in coastal hydrodynamics along with contributions by Serre (La Houille Blanche 8:374-388, 1953) and...

##### Decidability of first-order theories
2019-03-26
Speaker: Cristina Sernadas (CMAFcIO, Univ. Lisboa)
Some results and reduction techniques for proving decidability of mathematical theories and completeness of logics are presented. The crucial role of the theory of real closed ordered fields is explained. Selected illustrations from Euclidean Geometry to Quantum Logic are discussed....

##### Evolutionary quasi-variational and variational inequalities with constraints on the derivatives
2019-03-22
Speaker: Lisa Santos (Univ. Minho)
We study  the existence of quasi-variational and variational solutions to a class of nonlinear evolution systems in convex sets of Banach spaces describing constraints on a linear combination of partial derivatives of the solutions. The quasi-linear operators are of monotone type,...

##### On some applications of orthogonal polynomials in Mathematical-Physics
2019-03-08
Speaker: Renato Álvarez-Nodarse (Univ. Sevilla, Spain)
The orthogonal polynomials (OP) are very useful tools in solving problems not only in Mathematics but also in Physics and Engineering. Among them, the classical orthogonal polynomials (COP) deserve a special attention. The main reasons are, from my point of view, from one hand the fact that...

##### The finite element method in sheet metal forming simulation
2019-02-27
Speaker: Diogo Neto (DEM, Univ. Coimbra)
Numerical simulation is an indispensable tool for the successful implementation of digital manufacturing. The actual requirements for a higher degree of product customization dictate the use of simulation, allowing the virtual testing and validation of product, process and system design....

##### On finite simple quotients of triangle groups
2019-02-27
Speaker: Claude Marion (CMUP, Univ. Porto)
See the attached file...

##### Stochastic solutions for nonlinear partial differential equations
2019-02-20
Speaker: Rui Vilela Mendes (CMAFCIO, Univ. Lisboa)
A stochastic solution of a pde is a stochastic process that started from a point in the domain, generates a boundary measure which, when integrated over the initial condition, provides a local solution of the equation. Stochastic solutions not only provide new exact solutions for nonlinear...

##### On the classification of Schreier extensions of monoids with non-abelian kernel
2019-02-12
Speaker: Andrea Montoli (Univ. degli Studi di Milano, Italy)
We will show that any regular right Schreier extension of a monoid M by a monid A induces an abstract kernel, i.e. a monoid homomorphism from M to the factor monoid End(A)/Inn(A). If an abstract kernel factors through Epi(A)/Inn(A), then we associate to it an obstruction, which is an element...

##### Order-enriched solid functors
2019-02-12
Speaker: Lurdes Sousa (CMUC and IP Viseu)
Order-enriched solid functors enjoy many of the properties of their counterparts, including the detection of weighted colimits. We study two slightly different notions of order-enriched solidity and present several examples, which include functors of general varieties of ordered algebras and...

##### Portfolio selection in evolutionary algorithms
2019-01-30
Speaker: Andreia P. Guerreiro (CISUC, DEI-UC)
Evolutionary Algorithms (EAs) are algorithms inspired on the process of natural selection, and are among the most popular methods in multiobjective optimization. One of the main steps of an EA is selection which is aimed at focusing on the best individuals, but must also maintain a...

##### On function theory in the Euclidean space
2019-01-25
Speaker: Klaus Gürlebeck (Bauhaus-Universität Weimar, Germany)
We consider a function theory for functions defined in Rn with values in the quaternions or in Clifford algebras. The class of monogenic functions is firstly defined as the set of null solutions of a generalized Cauchy-Riemann system. Basic elements of this function theory (see also...

##### Geometry of mechanical control systems with applications
2019-01-23
Speaker: Sandra Isabel Ventura Ricardo (UTAD, Vila Real)
In this talk, a geometric setting for studying mechanical control systems is presented. A special class is distinguished: the class of geodesically accessible mechanical systems, for which the uniqueness of the mechanical structure is guaranteed (up to an extended point transformation)....

##### The 2-representation theory of Soergel bimodules of finite Coxeter type: a road map to the complete classification of all simple transitive 2-representations.
2019-01-23
Speaker: Marco Mackaaij (Univ. Algarve)
I will recall Lusztig's J-categories, which are fusion categories obtained from the perverse homology of Soergel bimodules. For example, for finite dihedral Coxeter type this fusion category is the semisimplified quotient of the module category of quantum so(3) at a root of unity, which...

##### From quantum to quantales and beyond
2019-01-22
Speaker: Pedro Resende (CAMGSD, Univ. Lisboa)
[The following abstract may also be found in the PDF file that is attached to this announcement] The axioms of quantum mechanics laid out by von Neumann involved Hilbert spaces and operators on them, and it soon became apparent that the properties of collections of operators are...

##### Axiom T_D and the Simmons sublocale theorem
2019-01-22
Speaker: Jorge Picado (CMUC, Univ. Coimbra)
A topological space X, more precisely its associated frame Ω(X) of open sets, has typically more sublocales than subspaces.  We will analyze some of Simmons (1980) and Niefield and Rosenthal (1987) results concerning sublocales induced by subspaces. The first result...

##### Tree oriented pullbacks
2019-01-16
Speaker: Flávio Ulhoa Coelho (Univ. São Paulo, Brazil)
See the attached file....

##### Functorial semantics and descent
2018-12-18
Speaker: Fernando Lucatelli Nunes (CMUC, Univ. Coimbra)
In [1], given a 2-category A satisfying suitable hypothesis, we give the semantic factorization via descent. This specializes to a new connection between monadicity and descent theory, which can be seen as a counterpart account to the celebrated Bénabou-Roubaud Theorem [2]. It also...

##### Compactly generated (T,V)-spaces
2018-12-18
Speaker: Willian Ribeiro (PhD Student, CMUC)
First studied by Hurewicz, compactly generated spaces arise as a convenient category for homotopy theory and algebraic topology [1]. The full subcategory of Top (the category of topological spaces and continuous functions) formed by the latter spaces is well-known to have nice properties: it...

##### Variational theory and spectral geometry of quantum graphs
2018-12-14
Speaker: James Kennedy (Univ. Lisboa)
The past decade has seen a pronounced growth of interest in differential operators defined on metric graphs, commonly known as quantum graphs. They offer the technical simplicity of one-dimensional objects, while often displaying complex behaviour akin to higher-dimensional ones, and are...

##### Truncated boolean representable simplicial complexes
2018-12-12
Speaker: Pedro V. Silva (CMUP, Univ. Porto)
These structures constitute the largest known class of simplicial complexes admitting a geometric/topological theory. We will present the main features of this class and some recent results (joint work with Stuart Margolis (Bar-Ilan) and John Rhodes (Berkeley))....

##### Information lost when resampling
2018-12-12
Speaker: Tilo Wiklund (Univ. of Uppsala, Sweden)
Various procedures in statistics rely on taking decisions based on data that has been resampled (usually with replacement). Examples include bootstrap-based confidence bounds and error estimates or "bagged" estimators. Since resampling is an additional source of randomness such...

##### Superalgebras with superinvolution
2018-12-12
Speaker: Herlisvaldo Costa Santos (UC|UP PhD programme student)
Our objective in this work is to provide primitive associative superalgebras a structure analogous to those for the algebras and to classify primitive superalgebras with superinvolution having a minimal superideal....

##### Homological invariants of blocks of Schur algebras
2018-12-06
Speaker: Steffen Koenig (Univ. Stuttgart, Germany)
Let S(n,r) be a classical or quantised Schur algebra with n ≥ r. Totaro determined the global dimension of classical S(n,r) and Donkin extended this result to quantum S(n,r). Ming Fang and I have determined the dominant dimension (which in some sense measures the strength of Schur-Weyl...

##### Representation type of algebras and quivers
2018-12-05
Speaker: Ivan Yudin (CMUC, Univ. Coimbra)
One of the first results one encounters in the standard university courses of algebra are classifications of equivalence classes of matrices under various transformations. If we are allowed to multiply the matrix in question from each side with an invertible matrix, then the corresponding...

##### On the topological complexity of surfaces
2018-12-05
Speaker: Lucile Vandembroucq (Univ. do Minho)
In this talk, we will consider the concept of topological complexity introduced by M. Farber to give a measure of the motion planning problem and discuss it for surfaces. In particular, we will see that the topological complexity of the Klein bottle and higher genus non-orientable surfaces...

##### Generalized weighted Lorentz spaces
2018-11-30
Speaker: Amiran Gogatishvili (Czech Academy of Sciences, Prague, Czech Republic)
We will define a new class of generalized weighted Lorentz spaces and we will present some properties of these spaces....

##### A mathematical model for a plant circadian oscillator
2018-11-28
Speaker: Adérito Araújo (CMUC, Univ, Coimbra)
Circadian rhythms are generated at the cellular level by a small but tightly regulated genetic network. They are observed in most organisms on earth and are known to play a major role in successful adaptation to the 24-h cycling environment. Understanding the molecular basis of cellular...

##### On the linear nature of pseudowords
2018-11-28
Speaker: Alfredo Costa (CMUC, Univ. Coimbra)
In this talk we see how the pseudowords in a finitely generated free profinite aperiodic semigroup are faithfully represented by labeled linear orders induced by factorizations of the pseudowords.This is joint work with Jorge Almeida, José Carlos Costa and Marc Zeitoun. ...

##### Kippenhahn's Theorem
2018-11-28
Speaker: Stephan Weis (CMUC, Univ. Coimbra)
The numerical range of a matrix is a convex subset of the plane of complex numbers (Toeplitz 1919, Hausdorff 1919) and equals the convex hull of a real algebraic curve (Kippenhahn 1951, Chien and Nakazato 2010). An interesting higher-dimensional analogue would be to write the joint...

##### Riemann-Hilbert problems in the theory of orthogonal polynomials
2018-11-23
Speaker: Amílcar Branquinho (CMUC, Univ. Coimbra)
In this talk we survey different aspects of the theory of orthogonal polynomials.Due to the ubiquity nature of orthogonal polynomials in modern science, their study has been performed from very many different points of view. Indeed, they can be considered from a purely algebraic point of...

##### On the existence of solutions for inextensible string equations
2018-11-23
Speaker: Ayk Telciyan (UC|UP PhD programme student)
In this talk, we analyze existence of solutions for inextensible string equations. In particular, we have results in two directions.On one hand, we find explicit traveling wave solutions for a system of hyperbolic conservation laws resulting from inextensible string equations via suitable...

##### Representations of fundamental groups of surfaces
2018-11-23
Speaker: Peter Gothen (CMUP, Univ Porto)
We consider representations of the fundamental group of a closed surface in the group SL(2,R). To each such representation one can associate an integer invariant called the Toledo invariant. A theorem of J. Milnor says that the absolute value of the Toledo invariant is less than or equal to...

##### Campanato spaces and applications in partial differential equations
2018-11-23
Speaker: David Jesus (UC|UP PhD Programme student)
In this talk I will discuss a generalization of Campanato's characterization of Holder continuity, and use these results to study the regularity of solutions to the non-homogeneous p-Laplace equation....

##### Boolean representable simplicial complexes
2018-11-23
Speaker: Maria Inês Couto (UC|UP PhD Programme student)
In this seminar we will discuss some properties of a particular class of simplicial complexes from a purely combinatorial perspective. The elements of this class, including all the matroids, admit a representation by a matrix with entries in the boolean semiring, so they are said boolean...

##### Lattice decomposition of modules and decomposition of categories
2018-11-21
Speaker: Pascual Jara (Univ. de Granada, Spain)
The decomposition of a module M in a direct sum M=M1+M2 does not produce, in general, a decomposition of the lattice L(M) of all submodules in a direct product of lattices L(M)=L(M1)xL(M2). When this happens we say M=M1+M2 is a lattice decomposition. These particular decompositions have...

##### Actions of Hopf algebras
2018-11-16
Speaker: Christian Lomp (CMUP, Univ Porto)
Group algebras and enveloping algebras of Lie algebras are examples of Hopf algebras. Automorphisms acting on rings as well as derivations acting on them are examples of Hopf algebra actions. Guided by these classical examples, we will motivate the study of Hopf algebra actions and consider...

##### Porous medium equations with advection
2018-11-16
Speaker: Nicolau Diehl (CMUC)
In this talk we present two types of results: one about decay estimates and another about global existence. Both results are obtained for bounded weak solutions of the Cauchy problem for Porous Medium Equations with advection through a fundamental energy estimate, an L^p -L^q estimate, and...

##### Categories, allegories
2018-11-14
Speaker: Igor Arrieta (UC|UP PhD programme student)
A binary relation from a set A to a set B is a subset of the cartesian product AxB. Moreover, a function f: A->B can be identified with a particular type of relation, namely the relation consisting of pairs (x,f(x)). Consequently, the usual category of sets can be regarded as a...

##### Geodesics in the space of Kähler metrics
2018-11-14
Speaker: Pedro Silva (UC|UP PhD programme student)
A Kähler manifold is a differentiable manifold with three geometric structures: a Riemannian metric, a symplectic form, and a complex structure, satisfying some compatibility conditions. The metrics and the symplectic forms for which these compatibility conditions are satisfied are...

##### Identification and simulation of flow in heterogeneous media: a model for oil extraction
2018-11-14
Speaker: Hugo Peña Gomez (UC|UP PhD Programme student)
The models of double porosity-permeability are used to described the dynamics of oil extraction (porous medium). The talk will be about presenting some aspects of this kind of models and a variation considering a particular medium structure. Some numerical results will be exposed. ...

##### On the group of a rational maximal bifix code
2018-11-07
Speaker: Alfredo Costa (CMUC, Univ. Coimbra)
A code is a set of words that freely generates a free submonoid of the free monoid. A specially relevant place in the theory of codes is occupied by the maximal bifix codes.In the last years, attention has been given to a process of "localization" in which one looks at the...

##### What is ... Pointfree Topology?
2018-10-31
Speaker: Jorge Picado (CMUC, Univ. Coimbra)
Pointfree topology deals with frames and locales, the pointfree counterparts of topological spaces. We shall present motivation for this approach to topology and its basic features and facts. We will emphasize some of the main differences between the two approaches and some advantages of the...

##### Leibniz algebras with invariant forms
2018-10-31
Speaker: Said Benayadi (Univ. de Lorraine, Metz, France)
In the case of Lie algebras, the left (resp. right) invariance of bilinear forms is equivalent to the invariance (or associativity) of these forms. However, it is not the case for Leibniz algebras.In this talk, we will give some results on the structures of Leibniz algebras which are...

##### The existence theorem of weak solution for the initial-boundary problem for Oskolkov's system of equations
2018-10-26
Speaker: Mikhail Turbin (Voronezh State Univ., Russia)
In the talk, the existence of weak solutions of the initial-boundary value problem describing the motion of weakly concentrated aqueous solutions of polymers (Oskolkov's system) is proved. The proof is based on the approximation-topological approach. On the first step, the operator equation...

##### Asymptotic theory of set partitions: a representation theory agenda
2018-10-24
Speaker: Jocelyn Lochon (Univ. Lisboa)
See the attached file....

##### 3-manifolds, knots and surfaces
2018-10-24
Speaker: João Miguel Nogueira (CMUC, Univ. Coimbra)
We will survey the motivation and history of 3-manifold topology, together with its twin subject of knot theory, giving special emphasis to the importance of surfaces on the understanding of these subjects. Under this framework, we will also review contributions of the speaker as suitable....

##### The numbers lead a dance
2018-10-24
Speaker: Poul Hjorth (Technical Univ. of Denmark, Lyngby, Denmark)
The unfolding of some strictly syntax based poetry is viewed from the perspective of dynamical systems theory. I will provide examples of this, in particular of a type of 13th century lyrical style, the generalisation of which gives rise to mathematical questions. In the search for answers...

##### Performance estimation of first-order methods for composite convex optimization
2018-10-18
Speaker: François Glineur (Université catholique de Louvain, Belgium)
Composite convex optimization consists in the minimization of a convex objective function equal to the sum of several convex functions with different properties, for example a smooth term and a nonsmooth term. We consider a large class of first-order methods designed to solve such...

##### Applied Mathematics: applications in biomedicine and biomathematics
2018-10-17
Speaker: Isabel Narra de Figueiredo (CMUC, Univ. Coimbra)
This talk focus on the description of some computer-assisted methods we have developed for the automatic interpretation of medical images and on some biomathematics models we have proposed to represent and simulate the early stages of colon cancer....

##### Limit groups and their profinite completion
2018-10-16
Speaker: Theo A. D. Zapata (Univ. de Brasília, Brazil)
In the last decades limit groups have been attracting the attention of many mathematicians, specially because they played a fundamental role in the recent solution of the outstanding Tarski problem on free groups. Two simple group-theoretical reasons for so much attention are the following:...

##### A categorical model for the Hopf fibration
2018-10-16
Speaker: Björn Gohla (GFM, Univ. Lisboa)
We give a description up to homeomorphism of S3 and S2 as classifying spaces  of small categories, such that the Hopf map S3 --> S2 is the realization of a  functor....

##### Investigation of the dynamics of the anti-Zener model
2018-10-12
Speaker: Vladimir Orlov (Voronezh State Univ., Russia)
We prove the solvability in the weak sense of the initial-boundary value problem for the multidimensional fractional model generated by the one-dimensional anti-Zener model. This model takes into account the prehistory of fluid motion along the particle trajectories. This model well...

##### Computing the indecomposable representations of left regular bands
2018-10-10
Speaker: Herman Goulet-Ouellet (UC|UP PhD programme student)
Left regular bands are a family of semigroups that enjoy many surprising properties. They have received some attention recently due to their link with Markov chains and hyperplane arrangements. In this talk, we will see how to compute the indecomposable projective representations of finite...

##### The boolean reflection of a frame and the Cantor-Bendixson derivative
2018-10-10
Speaker: Ana Belén Avilez (UC|UP PhD programme student)
We consider two categories, the category of frames and the category of complete boolean algebras. We know that a complete boolean algebra is always a frame, but we want to assign universally a complete boolean algebra to each frame. It turns out this is not always true, but there is a result...

##### Nonassociative products in nonassociative algebras with involution
2018-10-03
Speaker: Jose Ramón Brox López (CMUC)
Starting from the variety of associative, Lie, Jordan, or alternative algebras with involution (or involutive automorphism), we classify all the formal bilinear products of the formaxy+bx*y+cxy*+dx*y*+Ayx+Byx*+Cy*x+Dy*x*,formed with the help of the original product and the involution *...

##### Jacobi multipliers and nonholonomic Lagrangian systems
2018-09-26
Speaker: Patrícia Santos (ISEC, Coimbra)
Jacobi multipliers is a tool in the solution of problems in mechanics that provides Lagrangians descriptions and constants of motion for systems of ODE. In this seminar we establish the relation between Jacobi multipliers and nonholonomic Lagrangian systems where the dynamics is determined...

##### Polynomial mappings and sieved ultraspherical polynomials. An application involving an electrostatic model
2018-07-20
Speaker: Márcio N. de Jesus (IP Viseu)
We consider orthogonal polynomials (OP) via polynomial mappings in the framework of the semiclassical class. In particular, we analyze in detail cubic transformations for semiclassical OP of class at most 2, giving new examples of semiclassical OP of class 2 and providing integral...

##### Besov regularity of parabolic PDEs
2018-07-13
Speaker: Cornelia Schneider (Univ. Erlangen-Nuremberg, Germany)
The talk is concerned with the regularity of  solutions to linear and nonlinear evolution equations on nonsmooth domains.   In particular, we study the smoothness in a specific scale of Besov spaces. The regularity in these spaces determines the approximation order that...

##### Efficient and accurate Lagrangian-Eulerian numerical schemes for solving hyperbolic balance laws
2018-07-13
Speaker: Eduardo Abreu (UNICAMP, Brazil)
We develop first-order and high-resolution stable-fast numerical schemes for hyperbolic balance law models. A key feature is the dynamic tracing forward of the integral curves, which are locally conservative and preserve the natural setting of weak (entropic) solutions linked to the...

##### Numerical modelling of cell-renewal, pit patterns and crypt fission in colonic crypts
2018-07-10
Speaker: Giuseppe Romanazzi (UNICAMP, Brazil)
The colonic epithelium is filled in its internal walls by small cavities called crypts. These crypts are small tubular glands, containing proliferative cells, that obey to a programmed cell mechanism. The aberrant crypts occur as a consequence of an abnormal behavior of this programmed...

##### An Eilenberg-like Theorem beyond regular languages
2018-07-06
Speaker: Célia Borlido (Univ. Nice Sophia-Antipolis, France)
(See the attachment for the pdf version of the abstract).  Finite and profinite monoids have proved to be a powerful tool in the study of regular languages. On the one hand, Eilenberg's correspondence, establishing a bijection between certain classes of regular languages (so-called...

##### On the Clebsch-Gordan problem in positive characteristic
2018-07-05
Speaker: Stephen Donkin (Univ. of York, UK)
This is joint work with Samuel Martin. Consider the special linear group G of degree 2, over the complex numbers. There is one rational irreducible G-module V(r) for each non-negative integer r. The module V(r) has dimension r+1 and may be realised as the rth symmetric power of the...

##### Galois theory of graphs
2018-06-29
Speaker: George Janelidze (Univ. Cape Town, South Africa)
This talk is about graphs in the sense of graph theory (not in the sense used in category theory). It will be shown that their Galois theory is not very different from other set-valued combinatorial Galois theories considered before, in spite of what it seems, due to non-existence of various...

##### On generating cartesian closed subcategories of (T,V)-Cat
2018-06-29
Speaker: Willian Ribeiro (PhD Student, CMUC)
Generalizing the work of [1], we present the process of generating cartesian closed subcategories of (T,V)-Cat. From a fixed class C of objects, we form a new (reflective) subcategory whose objects are shown to be colimits of objects in C. For instance taking for C the class of compact...

##### Towards semi left exactness and Janelidze-Galois within the lax idempotent context
2018-06-29
Speaker: Fernando Lucatelli Nunes (CMUC)
This is a joint work with Maria Manuel Clementino. Our aim is to understand the analogues of semi-left exactness and the analogues of the basic ideas of Janelidze-Galois within the lax idempotent context. As it is usual, there are more than one possible approach to do so. Our first...

##### Tree conjecture on graphs and more colourings in polytopes
2018-06-29
Speaker: Raul Penaguião (Univ. Zurich, Switzerland)
We will talk about some chromatic invariants in graphs and polytopes, and see what are the consequences of a nice description of the kernel of these chromatic maps in important problems like the tree conjecture. We will see that the most general version of this problem is in the realm of...

##### Infinitesimal automorphisms of VB groupoids and algebroids
2018-06-27
Speaker: Alfonso Tortorella (KU Leuven, Belgium)
VB-groupoids and algebroids are vector bundle objects in the categories of Lie groupoids and Lie algebroids respectively, and they are related via the Lie functor. VB-groupoids and algebroids play a prominent role in Poisson and related geometries. In this talk, based on joint work with...

##### A problem-dependent inner approximation of the completely positive cone
2018-06-27
Speaker:

Mina Saee Bostanabad (PhD student, CMUC)

Motivated by the expressive power of completely positive programming and its dual, copositive programming, to encode hard optimization problems, many approximation schemes for the completely positive and copositive cones have been proposed and successfully used. For the completely positive...

##### Aspects of the Painlevé equations
2018-06-22
Speaker: Galina Filipuk (Univ. of Warsaw, Poland)
In this talk I shall present new nonlinear differential-difference equations related to the second Painlevé equation. I shall also review the basics of Nevanlinna theory (notation, examples and main theorems) and show how it can be applied to the study value distribution and growth...

##### Totally nonnegative unitriangular Toeplitz matrices and k-Schur functions
2018-06-21
Speaker: Cédric Lecouvey (Univ. François Rabelais, Tours, France)
The talk will focus on effective parametrisations of unitriangular Toeplitz matrices. We will first recall Thoma's parametrisation for the infinite matrices. Next, for matrices of rank k, we will see how one can recover Rietsch's parametrisation by k-tuple of nonnegative reals from the...

##### Spectral properties of variable-coefficient Toeplitz matrices
2018-06-15
Speaker: Helena Mascarenhas (CEAFEL, IST Lisboa)
Finite sections of classical Toeplitz matrices have been heavily studied in the last decades due to its several applications in particular to engineering problems. Variable-coefficient Toeplitz matrices generalize these ones. We will present results on the asymtotic behaviour of the ...

##### A new look at Calculus: how an old idea naturally leads from simple Algebra to the heart of Analysis
2018-06-13
Speaker: R. Michael Range (State University of New York at Albany, USA)
TBA...

##### Supercharacters for algebra groups and their geometric relations
2018-06-06
Speaker: João Dias (Univ. Lisboa)
Given any algebra group over any finite field one has a supercharacter theory constructed by P. Diaconis and I.M. Isaacs. And we may ask three questions:- How the supercharacter theory behaves with respect to change of field (i.e. finite field extensions)- Exists an object that contains all...

##### Mining chemical space for pharmacological rules: corneal permeation as an example
2018-06-06
Speaker:

Rui M. M. Brito (BSIM Therapeutics, IPN & Univ. Coimbra) and João H. B. Meireles (BSIM Therapeutics, IPN)

Drug discovery and development is a complex, long and expensive process involving searches in a multidimensional space and multi-objective optimization based on apparently unrelated target functions. The discovery of a new "small molecule" medicine depends on the identification of...

##### Supercharacters, Schur rings and association schemes
2018-05-30
Speaker: Carlos André (Univ. Lisboa)
In this talk, we describe and illustrate the connection of supercharacter theories of finite groups with Schur rings and association schemes, and we discuss possible generalisations to the context of (infinite) topological groups, in particular of totally disconnected compact and locally...

##### On the profinite topology on solvable groups
2018-05-23
Speaker: Khadijeh Alibabaei (CMUP, Univ. Porto)
We show that the wreath product of a finitely generated abelian group with a polycyclic group is a LERF group. This theorem yields as a corollary that the finitely generated free metabelian group is LERF, a result due to Coulbois.We also show that the finitely generated free solvable group...

##### Refined interlacing properties for zeros of paraorthogonal polynomials on the unit circle
2018-05-11
Speaker: Kenier Castillo (CMUC)
The purpose of this talk is to extend in a simple and unified way the known results on interlacing of zeros of paraorthogonal polynomials on the unit circle. These polynomials can be regarded as the characteristic polynomials of any matrix similar to a unitary upper Hessenberg matrix ...

##### Supercharacters of unitriangular groups and ramification graphs
2018-05-02
Speaker: Filipe Gomes (Univ. Lisboa)
Supercharacter theories are generalizations of the usual character theory of a group. In this talk, we present the basics of supercharacter theory, emphasizing the supercharacter theory of the unitriangular groups and its combinatorial interpretations. In the second part of the talk, we...

##### Identities in plactic and related monoids
2018-04-18
Speaker: António Malheiro (Univ. Nova de Lisboa)
The plactic monoid is a fundamental algebraic object which captures a natural monoid structure carried by the set of combinatorial objects of semistandard Young tableaux. Other monoids arise in a similar way by considering different combinatorial objects: the hypoplactic monoid...

##### The nine lemma in the S-Mal'tsev and in the S-protomodular settings
2018-04-17
Speaker: Andrea Montoli (Univ. degli Studi di Milano, Italy)
We investigate what is remaining of the nine lemma and of the denormalized nine lemma, respectively valid in a pointed protomodular and in a Mal'tsev category, in the context of partial protomodular and partial Mal'tsev categories, relatively to a class S of points. The results apply, among...

##### On homology monoids of simplicial abelian monoids
2018-04-17
Speaker: Alex Patchkoria (A. Razmadze Math. Institute of Tbilisi State Univ., Georgia)
The homology semimodules Hn(S) of a presimplicial semimodule S introduced in our earlier paper, are studied in the case where S is a simplicial abelian monoid. In particular, it is shown that if a simplicial abelian monoid A satisfies the Kan condition and the monoid of path components...

##### Mathematics and the world around us
2018-04-16
Speaker: Renato Álvarez-Nodarse (IMUS, Univ. Sevilla, Spain)
In 1623 Galileo wrote a beautiful book entitled “Il Saggiatore" in which appeared his famous statement that mathematics is the language of science. He claimed that to understand the Universe it is necessary to understand the language in which it is written, and it is written in...

##### Minimum energy curves in fluid environments
2018-04-13
Speaker: Luis Machado (ISR/UC and Univ. Trás-os-Montes e Alto Douro)
In path planning problems of autonomous underwater or aerial vehicles is frequently required to find a mission path that minimizes acceleration and drag while a vehicle moves from an initial position to a final target.Drag is a mechanical force that characterizes the resistance that the...

##### Entropy numbers of compact embeddings or radial and multi-radial subspaces of Sobolev spaces with applications.
2018-04-11
Speaker: Leszek Skrzypczak (Adam Mickiewicz Univ., Poznan, Poland)
See the attached file...

##### Price models in mean-field games
2018-03-21
Speaker:

Diogo Gomes (KAUST, Saudi Arabia)

In this talk, we introduce a price-formation model for electricity markets where a large number of small players can store and trade electricity. Our model is a constrained mean-field game (MFG) where the price is a  Lagrange multiplier for the supply vs. demand balance condition. Under...

##### Rewriting systems and commutativity of diagrams
2018-03-20
Speaker: Ivan Yudin (CMUC, Univ. Coimbra)
It is a common situation that given a set of commutative diagrams one needs to establish commutativity of another set of diagrams. The naive approach to the problem is to partition each diagram into smaller diagrams, so that each subdiagram is in the given set of commutative diagrams.In the...

##### Topological groups have representable internal actions
2018-03-20
Speaker: Maria Manuel Clementino (CMUC, Univ. Coimbra)
The actions of a group B on a group X correspond bijectively to the group homomorphisms from B to the group of automorphisms of X. This can be stated using representability of the functor 'actions on X' (see [2, 3]).In this talk we show the corresponding result for topological groups: The...

##### Sets of operators determined by the numerical range
2018-03-19
Speaker:

Janko Bracic (Univ. of Ljubljana, Slovenia)

See the attached file....

##### Some results on minors of Toeplitz matrices and the theory of symmetric functions
2018-03-16
Speaker: Miguel Tierz (Univ. Lisboa)
We study minors of Toeplitz matrices using the theory of symmetric functions. The symbols of the Toeplitz matrices can either be in the Szegö class or have Fisher-Hartwig singularities and the results apply both to minors of finite and of large dimension. As an application, and also...

##### Multiscale non-helical dynamos
2018-03-14
Speaker: Roman Chertovskikh (SYSTEC, Univ. Porto)
In this talk a short introduction to the magnetic dynamo theory (explaining how magnetic fields can be produced by flows of an electrically conducting fluid) as well as recent advances made by the speaker and his collaborators will be presented. Generation of large-scale magnetic field by...

##### A tour in extreme value laws
2018-03-09
Speaker: Jorge Soares (UC|UP PhD student)
In this talk, we analyse the stochastic process that arises from a dynamical system by evaluating an observable function along a given orbit of the system. Our goal is to give sufficient conditions for the existence of an Extreme Value Law for the considered process. We will present an...

##### Product formulas, generalized convolutions and integral transforms
2018-03-09
Speaker: Rúben Sousa (UC|UP PhD student)
It is well-known that the ordinary convolution is closely related with the Fourier transform. It is therefore natural to ask: for other important integral transforms, can we define generalized convolution operators having analogous properties? Actually, the answer depends on the existence of...

##### Phaseless rank and amoebas
2018-03-09
Speaker: António Goucha (UC|UP PhD student)
The phaseless rank of a nonnegative matrix M is defined to be the least k for which there exists a complex matrix N such that |N| = M, entrywise speaking. In optimization terms, it is the solution to the rank minimization of a matrix under phase uncertainty on the entries. This concept has a...

##### On the regularity of the vanishing ideals of graphs
2018-03-07
Speaker: Jorge Neves (CMUC, Univ. Coimbra)
In 2011, Renteria, Simis and Villarreal introduced a new class of binomial ideals associated to graphs. One associates to a simple graph, G, the vanishing ideal of a subset of a projective space over a finite field, parameterized by the edges of the graph. Although originally these ideals...

##### Numerical simulation of wave propagation from deep waters to very shallow waters, including changes over real bottoms
2018-02-21
Speaker: José Simão Antunes do Carmo (Department of Civil Engineering, University of Coimbra)
See the attached file...

##### A class of electromagnetic p(x,t)-curl systems: existence and uniqueness, blow-up and finite time extinction
2018-02-16
Speaker: Stanislav Antontsev (Univ. Lisboa & Inst. Hydrodynamics, Novosibirsk, Russia)
See the attached file...

##### On basic Fourier-Bessel expansions. Some related issues.
2018-02-09
We will present a summary of the latest developments with respect to expansions involving the Third Jackson q-Bessel function (or, Hahn-Exton q-Bessel function), with special emphasis regarding Fourier expansions related to some basic functions which are q-analogues...

##### Global higher regularity of solutions to p(x,t)-parabolic equations
2018-02-09
Speaker: Ivan Kuznetsov (Institute of Hydrodynamics, Novosibirsk, Russia)
See the attached file...

##### Application of data mining to structural biology
2018-02-07
Speaker: Irina S. Moreira (Center for Neuroscience and Cell Biology, Univ. Coimbra)
Contrary to the reductionist approach aimed at understanding individual components, the new data revolution allows the understanding of complicated interactions and pathways through the use of statistical Data Mining (DM). This is an active area of research in mathematic/computer science...

##### The intricacies of algebraic power series
2018-02-07
Speaker: Herwig Hauser (Univ. of Vienna, Austria)
A formal power series h(x) = sum a_n x^n is called algebraic if it satisfies a polynomial equation with coefficients in K[x]. Typical examples are rational series like (1+x)^(-1) or roots of polynomials like sqrt(1+x). In characteristic 0, it is an open problem to characterize the...

##### From Brauer trees to surface algebras
2018-01-24
Speaker: Karin Erdmann (Univ. of Oxford, UK)
We describe algebras constructed from graphs, and from surface triangulations, starting with Brauer tree algebras. We discuss how J. A. Green's walk around the Brauer tree generalizes....

##### The category of Brouwer operations: a basis for an understanding of choice sequences
2018-01-23
Speaker: Martin Hyland (Univ. of Cambridge, UK)
Intuitionism as first proposed by the Dutch mathematician L. E. J. Brouwer involved not simply the well-known refusal of the law of the excluded middle but a notion, that of free choice sequence which is prima facie incompatible with classical mathematics. The theory of choice sequences uses...

##### 2-Representations of dihedral and trihedral Soergel bimodules
2018-01-23
Speaker: Marco Mackaay (Univ. Algarve)
2-Representation theory of monoidal categories is the categorical analogue of representation theory of algebras. In my talk, I will discuss the 2-representation theory of (sub)-quotients of the monoidal categories of Soergel bimodules of affine type A1 and A2, which are closely related to...

##### Nonparametric first-order analysis of spatial and spatio-temporal point processes. Application to wildfire patterns
2018-01-19
Speaker: Wenceslao González Manteiga (Univ. Santiago de Compostela, Spain)
Spatial point patterns arise in a wide variety of scientific contexts, including seismology, forestry, geography and epidemiology. Wildfire is the most ubiquitous natural disturbance in the world and represents a problem of considerable social and environmental importance; particularly, in...

##### Quantum chaology in phase space through the Wigner transform
2018-01-10
Speaker: Luís Pereira (Univ. Lisboa)
The Wigner function is one of the five major equivalent formulations of Quantum Mechanics. The others being Schrödinger's Heisenberg's, Feynman's path integral and the Density Operator. The study of the quantization of classically chaotic systems in the 70's led to the generalization of...

##### Totalitarian random Tug-of-War games and Jensen's extremal equations
2017-12-15
Speaker: Fernando Charro (CMUC)
See the attached file.   ...

##### Some results on stochastic ageing and ordering
2017-12-15
Speaker: Idir Arab (CMUC, Univ. Coimbra)
The concepts of stochastic ageing and ordering, which play an important role in any reliability analysis, describe how a component or system improves or deteriorates with age, and how to decide which component or system is ageing faster (in some sense). Stochastic ordering of distributions...

##### Right-angled Artin groups: commensurability classification and subgroup intersection problem
2017-12-13
Speaker: Alexander Zakharov (CMUP, Univ. Porto)
The class of right-angled Artin groups (RAAGs) is a prominent class of groups which is widely studied in different branches of mathematics and computer science. Two groups are called commensurable if they have isomorphic subgroups of finite index. In the first part of the talk I will present...

##### Jacobi structures with a non-exact twist
2017-12-06
Speaker: Cornelia Vizman (West Univ. Timisoara, Romania)
We introduce a concept of twisted Jacobi structure that extends the twisted Jacobi structure of Petalidou and Nunes da Costa, as well as the twisted Poisson structure in wide sense (i.e. with an arbitrary 3-form).​W​e ​explain the​ one-to-one correspondence between...

##### The Kostant form of U(sl^+_n) and the Borel-Schur algebra
2017-11-29
Speaker: Ana Paula Santana (CMUC, Univ. Coimbra)
See the attached file...

##### The number of parking functions with center of a given length
2017-11-29
Speaker: Rui Duarte (Univ. Aveiro)
Let 1\leq r\leq n and suppose that, when the Depth-first Search Algorithm is applied to a given rooted labelled tree on n+1 vertices, exactly r vertices are visited before backtracking. Let R be the set of trees with this property. We count the number of elements of R.For this purpose, we...

##### Characterization of interpolation between Grand, small or classical Lebesgue spaces
2017-11-24
Speaker: Amiran Gogatishvili (Czech Academy of Sciences, Prague, Czech Republic)
See the attached file....

##### Some results on dependent random variables
2017-11-24
Speaker: Milto Hadjikyriakou (Univ. of Central Lancashire, Cyprus)
In recent years, concepts of dependence have been the focus of substantial research activity and applications of dependent random variables can be found in many different fields. In the first part of this talk some classes of dependent random objects are presented together with various...

##### Continuous weak selections on compact-like spaces
2017-11-21
Speaker: Tsugunori Nogura (Ehime Univ., Japan)
See attached file....

##### Regularity of interfaces for a Pucci type segregation problem
2017-11-17
Speaker: Verónica Quítalo (CMUC, Univ. Coimbra)
In this talk we will start giving a brief review about a segregation model with nonlinear diffusion that evolve to a free boundary problem as a motivation for our problem. Then we will present our latest results for the regularity of the limit solution as well as the regularity of the free...

##### On the combinatorics of a family of generalized Catalan triangles
2017-11-15
Speaker: Angela Mestre (Univ. Lisboa)
We generalize Aigner's array of the ballot numbers to a family of Riordan arrays. The entries of these generalized Catalan triangles are homogeneous polynomials in two variables which interpolate between the ballot numbers and the binomial coefficients. We show that the generalized Pascal...

##### Time-analyticity of fluid particle trajectories in ideal fluid flow
2017-11-08
In his 1815 manuscript, Cauchy showed that the equations governing the motion of particles in ideal fluid flow can be once integrated in time. This yields what is now known as the Cauchy invariants. The invariants are then used to derive recurrence relations for the time-Taylor coefficients...

##### The faceless problem
2017-11-03
Speaker: F. J. García-Pacheco (Univ. Cadiz, Spain)
Internal points were introduced in the literature of topological vector spaces to characterize the nest locally convex vector topology. Later on, they have been generalized to the context of real vector spaces by means of the inner points. Inner points can be seen as the most opposite...

##### First-order, stationary mean-field games with congestion
2017-10-27
Speaker: Levon Nurbekyan (KAUST, Saudi Arabia)
Mean-field games (MFGs) are models for large populations of competing, rational agents that seek to optimize a suitable functional. In the case of congestion, this functional takes into account the difficulty of moving in high-density areas. In this talk, I will present a recent contribution...

##### On the representation theory of the Infinite Unitriangular group
2017-10-18
Speaker: Jocelyn Lochon (Univ. Lisboa)
Let U(q) denote the set of infinite nilpotent matrices over the finite field with q elements, called infinite unitriangular group. It is a wild group (not type I), thus the irreducible representation do not admit any reasonable parametrization.Nevertheless the set of all characters...

##### Integers and ideals: there and back again
2017-10-18
Speaker: Peter Lombaers (UC|UP PhD student)
In number theory, when you try to solve an equation in a number field, it is often more convenient to work with ideals than with integers. This stems from the fact that ideals have unique factorization, but integers may not. I will explain the advantages and difficulties of this method...

##### Introducing (T,V) -categories
2017-10-18
Speaker: Willian Silva (UC|UP PhD student)
In this seminar we introduce the concept of (T,V)-categories through its fundamental examples. In order to do so, we explore the concepts of monads and quantales, also with examples. We finish relating to the work on cartesian closed categories. The seminar takes place in...

##### SOS versus SDSOS polynomial optimization
2017-10-18
Speaker: Mina Saee Bostanabad (UC|UP PhD student)
It is NP-hard to decide whether a polynomial is nonnegative, however, semidefinite programming can be used to decide whether a polynomial is a sum of squares of polynomials (SOS) in a practically efficient manner. In the context of polynomial optimization, it has become usual to substitute...

##### Inverse monoids and immersions of cell complexes
2017-10-17
Speaker: Nora Szakács (CMUP, Univ. Porto)
In the talk, we study immersions between cell complexes using inverse monoids. By an immersion f : D -> C between cell complexes, we mean a continous map which is a local homeomorphism onto its image, and we further suppose that commutes with the characteristic maps of the cell complexes....

##### Deformations of coisotropic submanifolds in Jacobi manifolds
2017-10-11
Speaker: Alfonso Tortorella (CMUC, Univ. Coimbra)
Originally introduced by Kirillov and Lichnerowicz, Jacobi manifolds encompass, unifying and generalizing, locally conformal symplectic/Poisson manifolds and (non-necessarily coorientable) contact manifolds. In this talk, in order to investigate the coisotropic deformation problem, we attach...

##### Oscillatory and nonoscillatory behavior of a differential delay system of order n
2017-10-11
See file attached...

##### Embeddings of weighted Morrey spaces
2017-09-29
Speaker: Dorothee Haroske (Univ. Jena, Germany)
See the attached file...

##### Lagrangian controllability for the 3D Navier-Stokes equations
2017-09-27
Speaker: Vahagn Nersesyan (Univ. Versailles, France)
In the Eulerian approach, the motion of an incompressible fluid is usually described by the velocity field which is given by the Navier-Stokes system. The velocity field generates a flow in the space of volume-preserving diffeomorphisms. The latter plays a central role in the Lagrangian...

##### Joins of closed sublocales, coframes of sublocales, and frames of sublocales
2017-09-12
Speaker: Aleš Pultr (Charles Univ., Prague, Czech Republic)
Topics to be covered: 1. The frame Sc(L) of joins of closed sublocales of a locale L; motivation (scatteredness). 2. The relation of Sc(L) to the coframe of sublocales S(L). 3. Sc(L) as a "discrete cover" of L, modelling discontinuity. 4. Comparing Sc(L) with the frame of...

##### Towards a pseudoequational proof theory
2017-07-13
Speaker: Jorge Almeida (CMUP, Univ. Porto)
A new scheme for proving pseudoidentities from a given set Σ of pseudoidentities, which is clearly sound, is also shown to be complete in many instances, such as when Σ defines a locally finite variety, a pseudovariety of groups or, more generally, of completely simple...

##### Variational obstacle avoidance problem on Riemannian manifolds
2017-07-11
Speaker: Margarida Camarinha (CMUC, Universidade de Coimbra)
Motion planning with obstacle avoidance is an important task in the field of robotics. Many methods for autonomous vehicle navigation with obstacle avoidance have been developed in the last few decades. I will talk about a variational obstacle avoidance problem on a Riemannian manifold and...

##### A new signature of quantum phase transitions from the numerical range
2017-07-10
Speaker: Stephan Weis (Université libre de Bruxelles, Belgium)
A quantum phase transition is a ground state phenomenon in an infinite lattice model with various defining key properties. We focus on two of them and point out their signatures in finite lattice models: Non-analyticity of the ground state energy and strong variation of the entropy of...

##### Overlapping domain decomposition algorithms for singularly perturbed parabolic problems
2017-06-28
Speaker: Sunil Kumar (Indian Institute of Technology, India)
in the attached file...

##### On the Kantor product
2017-06-28
Speaker: Ivan Kaygorodov (Univ. Federal do ABC, Santo André, Brazil; Siberian State Aerospace Univ., Krasnoyarsk, Russia)
Kantor defined the conservative algebras as an generalization of Lie and Jordan algebras. There are many relations between conservative algebras and other non-associative algebras. We will talk about some classical papers of Kantor and some new results obtained in some joint work with Yu....

##### On a quadratic Schrödinger system
2017-06-16
Speaker: Filipe Oliveira (Univ. Nova de Lisboa)
See the attached file...

##### Nonorientable hypermaps
2017-06-13
Speaker: Daniel Marques Pinto (CMUC, University of Coimbra)
Topologically, a hypermap is a cellular embedding of a connected hypergraph into a closed connected surface. If that underlying surface is orientable, we say that the hypermap is orientable. Otherwise, the hypermap is called nonorientable. We will present some results about nonorientable...

##### Radial and block-radial subspaces of Sobolev and Besov spaces: regularity, decay and compactness
2017-06-09
Speaker: Leszek Skrzypczak (Adam Mickiewicz Univ., Poznan, Poland)
See the attached file...

##### Analytical and numerical methods for a class of second and third kind Volterra integral equations
2017-06-02
Speaker: Sonia Seyed Allaei (CMUC)
See the attached file. ...

##### Two mathematical approaches in ophthalmology
2017-06-01
Speaker: Maryam Khaksar Ghalati
TBA Maryam Khaksar Ghalati is a former PhD student of the Joint PhD Program UC|UP, in the area "Numerical Analysis andOptimization" under the supervision of professors Adérito Araújo and Sílvia Barbeiro. ...

##### Reducibility of nilpotent cone for G-Higgs bundle moduli space
2017-06-01
TBA Azizeh Nozad is a Postdoctoral fellow at Faculty of Science, University of Lisbon....

##### Statistical instability for the contracting Lorenz flow
2017-06-01
Speaker: Muhammad Ali Khan (UP student)
TBA Muhammad Ali Khan is a PhD student of the Joint PhD Program UC|UP, working at the University of Porto, in the areaof "Dynamical Systems" under the supervision of professor José Ferreira Alves.  ...

##### Semisimple Hopf actions and factorization through group actions
2017-05-31
Speaker: Deividi Pansera (Univ. Porto)
See the attached file....

##### Singularities of non-commutative integrable systems
2017-05-30
Speaker: Rui Loja Fernandes (Univ. of Illinois at Urbana-Champaign, USA)
Integrable systems that appear in "nature" always have singularities and there is a well-known theory of non-degenerate singularities, which are divided into 3 classes: elliptic, focus-focus and hyperbolic classes. However, in the case of non-commutative integrable systems, such a...

##### On Besov spaces of smoothness zero
2017-05-26
Speaker: Oscar Domínguez (CMUC)
see the attached file...

##### Extensions of Herstein's theory on Jordan (and Lie structures) to more general associative systems
2017-05-24
Speaker: Fernando Montaner (Univ. Zaragoza, Spain)
In the mid 1950s Herstein's opened a field of research which had as its aim the study of the structures of Lie and Jordan algebras that can be obtained from an associative algebra (possibly, with an involution) by endowing it with the Lie product ([xy]=xy-yx) or the Jordan product...

##### Early exercise boundaries for American-style knock-out options
2017-05-18
Speaker: José Carlos Dias (ISCTE-IUL Business School)
Under mild assumptions, this paper proposes a novel representation for the early exercise boundary of American-style double knock-out options in terms of the simpler optimal stopping boundary of a nested single barrier American-style contract. Therefore, and from now on, any single-factor...

##### Characterization and estimation of the upcrossings index
2017-05-17
Speaker:

Ana Paula Martins (CMA-UBI, Univ. da Beira Interior)

Extreme Value Theory aims to predict occurrence of rare events, which in numerous situations have disastrous impacts, making an adequate estimation of the parameters related with such events of primordial importance in Statistics of Extremes. The extremal index and the upcrossings index play...

##### Combinatorics and HOMFLYPT invariants of knots
2017-05-17
Speaker: Marko Stosic (IST, Lisboa)
HOMFLYPT invariants are one of the most important and general invariants in the study of the topological properties of knots. Apart from the purely knot-theoretic interest, they are related to numerous different areas of mathematics and physics, including representation theory, operator...

##### On a generalized nonlinear heat equation in Besov and Triebel-Lizorkin spaces
2017-05-10
Speaker: Franka Baaske (Friedrich-Schiller-Univ. Jena, Germany)
See the attached file...

##### The \theta-parareal schemes
2017-05-03
Speaker: Richard Tsai (Univ. of Texas at Austin, USA)
We propose a variant of the parareal method for parallel-in-time computation of time dependent problems. We call it the θ-parareal schemes because it formally resembles the θ-schemes for discretizing time dependent partial differential equations. We analyze the linear...

##### Morrey spaces on domains: different approaches and growth envelopes
2017-04-28
Speaker: Cornelia Schneider (Univ. Erlangen-Nuremberg, Germany)
see the attached file...

##### Corecursive algebras
2017-04-26
Speaker: Jiří Adámek (Tech. Univ. Braunschweig, Germany)
There are various models of algebras in which certain recursive equations are uniquely solvable. A simple one was introduced by Capretta, Uustalu and Vene: given an endofunctor H, recursive equations are formalized as coalgebras for H. An algebra for H is called corecursive if every...

##### Polytopes, slack ideals and psd-minimality
2017-04-26
Speaker: João Gouveia (CMUC / Univ. Coimbra)
The slack ideal is an algebraic object that codifies the geometry of a polytope. This notion was motivated by the study of psd-minimality of polytopes: A d-polytope is said to be psd-minimal if it can be written as a projection of a slice of the cone of d+1 by d+1 positive semidefinite...

##### A symbolic approach to perturbed second degree forms: study of the case of perturbed Chebyshev polynomials
2017-04-19
Speaker: Zélia Rocha (CMUP, Univ. Porto)
See the attached file....

##### Graph complexes and configuration spaces of points
2017-04-19
Speaker: Ricardo Campos (ETH Zürich, Switzerland)
Given a manifold M, one can study the configuration space of n points on the manifold, which is the subspace of M^n in which two points cannot be in the same position. The study of these spaces from a homotopical perspective is of interest in very distinct areas such as algebraic topology or...

##### An introduction to L_\infty algebras and L_\infty algebroids
2017-04-19
Speaker: Raquel Caseiro (CMUC/Univ. Coimbra)
L∞ algebras are natural generalizations of Lie algebras from a homotopy theoretical point of view. The original definition dates back to 1992 by J. Stasheff and T. Lada and the idea is to weaken the condition imposing that the Lie bracket satisfies the Jacobi identity. Instead one asks...

##### How to extend an edge colouring?
2017-04-19
Speaker: António Girão (Univ. Cambridge, UK)
See attached pdf file....

##### Fast algorithms for high frequency wave propagation
2017-04-12
Speaker: Bjorn Engquist (Univ. of Texas at Austin, USA)
Direct numerical approximation of high frequency wave propagation typically requires a very large number of unknowns and is computationally very costly. We will discuss two aspects of this type of problem. One is the development and analysis of fast algorithms...

##### Magnitude homology
2017-04-11
Speaker: Tom Leinster (Univ. of Edinburgh, UK)
Magnitude homology is a homology theory of enriched categories, proposed by Michael Shulman late last year. For ordinary categories, it is the usualhomology of a category (or equivalently, of its classifying space). But for metric spaces, regarded as enriched categories à la...

##### General monotonicity concept and its applications
2017-04-07
Speaker: Sergey Tikhonov (CRM, Barcelona, Spain)
TBA...

##### Volterra integral equations for non linear partial differential equations of integrable type
2017-04-07
Speaker: Luisa Fermo (Univ. of Cagliari, Italy)
Nonlinear partial differential equations (NPDE) of integrable type have important physical applications. They are used to describe electromagnetic waves in optical fibers, surface wave dynamics, charge density waves, breaking wave dynamics etc. Their corresponding initial value problem (IVP)...

##### Optimal transport, PDEs and geometry
2017-04-05
Speaker: Dmitry Vorotnikov (CMUC, Univ. Coimbra)
Various nonlinear evolutionary partial differential equations (coming from physics, fluid and solid mechanics, biology, chemistry etc.) can be viewed as geodesic equations or gradient flows on infinite-dimensional Riemannian structures.Understanding the underlying geometry of a PDE...

##### Combinatorics in minimal case completions of matrix pencils
2017-04-05
Speaker: Marija Dodig (Univ. Lisboa)
In this talk we shall present some combinatorial tools in resolving matrix pencil completion problems. Also, we shall explain the concept of minimal completions, and present the solution of the general matrix pencil completion problem in the minimal case....

##### Solution of a matrix problem coming from differential equations
2017-04-05
Speaker: Charles R. Johnson (College of William and Mary, Williamsburg, USA)
TBA...

##### Resolvability of topological spaces
2017-03-31
Speaker: István Juhász (Alfréd Renyi Inst. of Mathematics, Budapest, Hungary)
A topological space X is called λ-resolvable, where λ is a (finite or infinite) cardinal, if X contains λ many pairwise disjoint dense subsets. X is maximally resolvable if it is ∆(X)-resolvable, where ∆(X) = min{|G| : G open, G =/= ∅} .The...

##### Hopf algebras and Ore extensions
2017-03-29
Speaker: Christian Lomp (Univ. Porto)
Enveloping algebras of Lie algebras are typical examples of Hopf algebras. Some of them can be presented as iterated Ore extensions, which are a sort of non-commutative polynomial rings. This raises the natural question as to which Ore extensions over a Hopf algebras R admit a Hopf algebra...

##### An introduction to Sasakian manifolds
2017-03-22
Speaker: Antonio de Nicola (CMUC, Univ. Coimbra)
I will introduce the first elements of contact and almost contact geometry, starting from the notion of contact manifold. I will briefly mention its relation with symplectic geometry as well as some application to physics. I will present the notions of normality and compatible metric in an...

##### Renormalized transport of inertial particles
2017-03-22
Speaker: Marco Martins Afonso (CMUP, Univ. Porto)
We study how an imposed fluid flow - laminar or turbulent - modifies the transport properties of inertial particles, namely their terminal velocity, effective diffusivity, and concentration following a point-source emission.Such quantities are investigated by means of analytical and...

##### Nonparametric models for extreme risks with urn models
2017-03-22
Speaker: Juerg Husler (Univ. of Bern, Switzerland)
Extreme risk is often modelled with parametric or semi-parametric models. Here we present nonparametric models for a large setup of risks where the underlying process is not stationary, but is changing with time. The approach is based on the flexible class of urn models. This is made...

##### On some categorical-algebraic conditions in S-protomodular categories
2017-03-21
Speaker: Andrea Montoli (Università degli Studi di Milano, Italy)
We study, in the context of S-protomodular categories, relative versions of some categorical-algebraic conditions already considered for semi-abelian categories, like the algebraic coherence and the local algebraic cartesian closedness. The goal is to obtain a hierarchy between...

##### Interesting algebras between Kleisli and Eilenberg-Moore
2017-03-21
Speaker: Lurdes Sousa (CMUC, IP Viseu)
We investigate important categories lying strictly between the Kleisli category and the Eilenberg-Moore category, for a Kock-Zöberlein monad on an order-enriched category. The situation is dramatically different from the particular case of idempotent monads, for which there are no...

##### Characterization of Sobolev spaces through functionals without derivatives dependence
2017-03-17
Speaker: Ana Margarida Ribeiro (CMA, Univ. Nova de Lisboa)
Extending previous works due to Bourgain, Brézis, and Mironescu [J. Anal. Math. 87 (2002)] and Leoni and Spector [J. Funct. Anal. 261, 10 (2011)], we provide new characterizations of Sobolev spaces in terms of functionals involving difference quotients. These characterizations have...

##### Connection techniques for the study of the structure of algebraic objects
2017-03-15
Speaker: José M. Sánchez (CMUC)
After recalling classical results in order to place our work, we summarize the evolution of the connection techniques and its useful applications to the study of split decompositions. By making use of these techniques, we focus our attention on the study of the structure and the simplicity...

##### On the construction of complex algebraic surfaces
2017-03-08
Speaker: Carlos Rito (CMUP, Univ. Porto)
Surfaces of general type are far from being classified. Frequently the construction of a single example is a challenge, even for the ones with low values of the invariants. The most efficient methods of construction are classical: quotients by the action of a group and coverings. In this...

##### Extremal behavior of chaotic dynamical systems
2017-03-08
Speaker: Ana Cristina Moreira Freitas (CMUP, Univ. Porto)
This talk is about the study of rare events for chaotic dynamical systems.We will address this issue by two approaches. One regards the existence of Extreme Value Laws (EVL) for stochastic processes obtained from dynamical systems, by evaluating an observable function (which achieves a...

##### On a regularity conjecture for degenerate elliptic pdes
2017-02-22
Speaker: José Miguel Urbano (CMUC, Univ. Coimbra)
We establish a new oscillation estimate for solutions of nonlinear partial differential equations of degenerate elliptic type, which yields a precise control on the growth rate of solutions near their set of critical points. We then apply this new tool in the investigation of a longstanding...

##### Non Fickian diffusion in porous media
2017-02-22
Speaker: José Augusto Ferreira (CMUC, Univ. Coimbra)
Transport processes in porous media have being described by the classical convection-diffusion equation for the concentration coupled with an elliptic equation for the pressure and Darcy’s law for the velocity. Despite the popularity of this model, gaps between experimental data...

##### Paths to uniqueness of critical points and applications
2017-02-17
Speaker: Hugo Tavares (U. Lisboa)
In this talk we show a unified and general criterion for the uniqueness of critical points of a functional in the presence of constraints such as positivity, boundedness, or fixed mass. Our method relies on convexity properties along suitable paths. To illustrate our method we present a...

##### Constrained partitions in graphs: bio and financial applications
2017-02-15
Speaker: Pedro Martins (IPCoimbra and CMAF-CIO)
This seminar addresses partition problems in graphs, from an applied perspective. We discuss results and formulations, ranging from very restrictive partition components (partition into cliques) to less restrictive ones (partition into trees - a forest). We also compare these results with...

##### O Naufrágio da Namíbia. Um Espólio Bem Guardado
2017-02-15
Speaker: José Malhão Pereira (Academia de Marinha e Centro de História das Ciências da UL)
Na manhã do dia 1 de Abril de 2008, pessoal da empresa Namdeb da Namíbia, removendo a areia junto à costa a cerca de 18 quilómetros da foz do rio Orange, que faz a fronteira com a África do Sul, encontraram madeira, lingotes de cobre e duas peças de...

##### The deformation cohomology of a Lie groupoid and applications to rigidity
2017-02-10
Speaker: João Nuno Mestre (CMUC/Univ. Coimbra)
In this talk we discuss deformations of Lie groupoids and introduce the cohomology which controls them. We then study some of its properties, and give a geometric interpretation for it in low degrees. We will also look at relations with other cohomologies: deformation cohomologies for...

##### Optimal simplex finite-element approximations of arbitrary order in curved domains circumventing the isoparametric technique
2017-02-10
Speaker: Vitoriano Ruas (Univ. Pierre et Marie Curie, Paris, and Catholic Univ., Rio de Janeiro)
One of the reasons for the undeniable success of the finite-element method in the applied sicences is its great versatility to deal with different types of geometries. This is particularly true of problems posed in curved domains of arbitrary shape. In this case method's isoparametric...

##### The combinatorics of noncrossing and nonnesting partitions
2017-02-08
Speaker: Ricardo Mamede (CMUC, Univ. Coimbra)
After a brief introduction to abstract Coxeter systems using a combinatorial approach based on words, we discuss recent developments on two combinatorial objects associated to the classical Coxeter groups: noncrossing and nonnesting partitions....

##### On the representation theory of some Noetherian algebras
2017-02-08
Speaker: Paula Carvalho (CMUP, Univ. Porto)
I will present some classes of Noetherian algebras that I have been studying regarding their representation theory; down-up algebras and skew polynomial rings, presenting past and present results. If time allows, another class of algebras will be introduced for which it is unknown when they...

##### Approximation in Morrey spaces
2017-02-03
Speaker: Alexandre Almeida (Univ. Aveiro)
We introduce a new subspace of Morrey spaces where the approximation by nice functions is possible in Morrey norm. In particular, we obtain an explicit description of the closure of the set of all infinitely differentiable compactly supported functions in Morrey spaces....

##### Dual enrichment and Isbell Duality
2017-01-30
Speaker: Martin Hyland (Univ. of Cambridge, UK)
The category of presheaves on a given small category is enriched in the category of presheaves on its opposite. This piece of Category Theory folklore is under appreciated perhaps because it is not clear what to do with it. I shall discuss versions of this phenomenon and how it looks from...

##### Sign patterns of coefficients of power series associated with the spectra of positive matrices
2017-01-30
Speaker: Thomas Laffey (Univ. College Dublin, Ireland)
See attached pdf file....

##### Statistical detection of some topological and geometric features
2017-01-26
Speaker: Antonio Cuevas (Univ. Autónoma de Madrid, Spain)
The subject of this talk is closely related to the theories of set estimation and manifold estimation. Our object of interest is a, possibly lower-dimensional, compact set M in Rd. The general aim is to identify (via stochastic procedures) some qualitative or quantitative features of M of...

##### Multiple orthogonal polynomials and some of their applications
2017-01-26
Speaker: Walter Van Assche (KU Leuven, Belgium)
Multiple orthogonal polynomials are polynomials in one variable that satisfy orthogonality conditions with respect to several measures. I will briefly give some general properties of these polynomials (recurrence relation, zeros etc.). These polynomials have recently appeared in many...

##### A geometric glimpse to certain classes of first order PDE's
2017-01-26
Speaker: Franco Magri (Univ. degli Studi di Milano-Bicocca, Italy)
The purpose of the talk is to illustrate , on a simple example, how ideas from the theory of singularities, from the theory of Riemannian and Frobenius manifolds, and from Hamiltonian mechanics beautifully intertwine in the study of certain classes of first order PDE's of hydrodynamic...

##### Internal Schensted insertion and tableau-switching involution
2017-01-18
Speaker: Olga Azenhas (CMUC, Univ. Coimbra)
Robinson-Schensted insertion and Sch\"utzenberger jeu de taquin are central operations in algebraic combinatorics with deep applications in other areas. Knuth transformations on words explain how they are related by showing what they do on words. This allows to replace insertion...

##### On ARL-unbiased c-charts for INAR(1) Poisson counts
2017-01-13
Speaker: Manuel Cabral Morais (CEMAT, Univ. Lisboa)
Counts of nonconformities are frequently assumed to have a Poisson distribution. The integer and asymmetrical character of this distribution and the value of its target mean may prevent the quality control operator to deal with a chart with a pre-specified in-control average run length (ARL)...

##### The ADR algebra and other strongly quasihereditary algebras
2017-01-04
Speaker: Teresa Conde (Univ. Stuttgart, Germany)
Quasihereditary algebras were introduced by Cline, Parshall and Scott in order to deal with highest weight categories arising from Lie theory. A prototype for quasihereditary algebras are the Schur algebras.Given a finite-dimensional algebra A, we may associate to it a special endomorphism...

##### Some tools for the study of Cartan connections on proper Lie groupoids
2016-12-16
Speaker: Giorgio Trentinaglia (IST, Lisboa)
I will describe some results of mine suggesting a clear strategy for the study of the following basic questions - about which little seems to be known - concerning Cartan (i.e. multiplicative) connections on proper Lie groupoids: a) What are the obstructions to the existence of Cartan...

##### Castelnuovo-Mumford regularity and graph invariants
2016-12-16
Speaker: Jorge Neves (CMUC, Univ. Coimbra)
The work of R. Stanley exposed a strong link between the theory of ideals of a polynomial ring generated by monomials and the theory of simplicial complexes. Recently, other bridges have been established between combinatorial structures and classes of ideals not necessarily generated by...

##### Systems of partial differential equations arising from population dynamics and neuroscience: Free boundary problems as a result of segregation
2016-12-14
Speaker: Verónica Quítalo (Univ. Coimbra - CoLab UT Austin Portugal Program)
In this talk we will present some two phase free boundary problems arising from population dynamics. We will focus on systems with fully nonlinear diffusion and local interaction, and linear systems with a (non local) long range interaction. In the long range model, the growth of a...

##### Derivations and generalized derivations of non-associative algebras
2016-12-14
Speaker: Ivan Kaygorodov (Univ. Federal do ABC, Brazil)
A famous theorem of Jacobson talks about the nilpotency of any finite dimensional Lie algebra with an invertible derivation. We will discuss about some generalizations of this theorem for the case of Leibniz derivations and other non-associative algebras. In particular, we will talk about...

##### How to centralize and normalize quandle extensions
2016-12-13
Speaker: Mathieu Duckerts-Antoine (CMUC)
During this talk, we will study different classes of quandle homomorphisms defined with respect to a fundamental reflection of the category of quandles into its full subcategory of trivial quandles. I will recall the notion of a central extension and of a normal extension coming from...

##### A short survey on Copositive and Completely Positive optimization
2016-12-07
Speaker:

Paula Amaral (Univ. Nova de Lisboa)

Copositive (Cop) and Completely Positive (ComP) Optimization is a recent and growing area of research. It has shown that several NP-hard optimization problems can be expressed as Cop or Comp programs, linear programs over the convex cone of copositive or completely positive matrices.In this...

##### Geometric regularity theory for fully nonlinear elliptic equations
2016-12-07
Speaker: Edgard A. Pimentel (Univ. São Carlos, Brazil)
In this talk, we examine the regularity theory for fully nonlinear elliptic equations of the form F(D^2 u)=f(x) where F is a (λ,Λ)-elliptic operator and f:B1→ℝ is a continuous source term, in appropriate Lebesgue spaces. We recur to a set of tools known as geometric-...

##### Finite dimensional Poisson algebras
2016-12-07
See attached file. ...

##### On locally conformal symplectic manifolds of the first kind
2016-12-06
Speaker: Juan Carlos Marrero (Univ. of La Laguna, Tenerife, Spain)
In this talk, I will present some recent results on locally conformal symplectic manifolds of the first kind. In fact, under certain topological restrictions related with the compactness of the canonical foliation, we will discus a structure theorem for these manifolds. In the non compact...

##### On Taken's Last Problem: times averages for heteroclinic attractors
2016-12-02
Speaker: Alexandre A. Rodrigues (CMUP, Univ. Porto)
In this talk, after giving a technical overview about the topic, I will discuss some properties of a robust family of smooth ordinary differential equations exhibiting tangencies for a dense subset of parameters. We use this to find dense subsets of parameter values such that the set of...

##### Singularities of vector fields and the dimension of groups of holomorphic diffeomorphisms
2016-12-02
Speaker: Helena Reis (CMUP, Univ. Porto)
The group of holomorphic diffeomorphisms, Aut(M), of a compact complex manifold M is a Lie group of finite dimension. To provide bounds for the dimension of these groups is a classical problem in complex analysis. It is well known that the dimension of Aut(M) cannot be bounded in terms of...

##### Topological mirror symmetry for parabolic Higgs bundles
2016-11-30
Speaker: André Oliveira (CMUP, Univ. Porto)
See attached file....

##### The C^{p'}-regularity conjecture in the plane
2016-11-25
Speaker: Damião Araújo (UNILAB and UFPB, Brazil)
We establish a new oscillation estimate for solutions of nonlinear partial differential equations of elliptic, degenerate type. This new tool yields a precise control on the growth rate of solutions near their set of critical points, where ellipticity degenerates. As a consequence, we are...

##### Extreme supercharacters of the infinite unitriangular group
2016-11-23
Speaker: Carlos André (CEAFEL, Univ. Lisboa)
We define extreme supercharacters of the infinite unitriangular group, introduce the ramification scheme associated with the classical supercharacter theories of the finite unitriangular groups and describe how extreme supercharacters of the infinite unitriangular group appear as weak limits...

##### Smoothness Morrey spaces and their envelopes
2016-11-18
Speaker: Susana Moura (CMUC, Univ. Coimbra)
See attached file....

##### A meeting between Sobolev, Bessel, Hölder, Lorentz and Karamata in order to discuss optimal embeddings and some open problems
2016-11-18
Speaker: Júlio Neves (CMUC, Univ. Coimbra)
In this talk we give a short survey on the results of embeddings of Sobolev type spaces into Hölder type spaces, including as well the famous result of Brézis and Wainger about almost Lipschitz continuity of elements of the Sobolev space with super-critical exponent of...

##### Monoidal categorical Galois theory
2016-11-15
Speaker: Dimitri Chikhladze (CMUC, Univ. Coimbra)
In this talk I will explain a generalization of the categorical Galois theory of Janelidze to a context of monoidal category theory, and its relationship with the work of Deligne on Tannakian categories....

##### Equidivisible pseudovarieties of semigroups
2016-11-15
Speaker: Alfredo Costa (CMUC, Univ. Coimbra)
A semigroup is said to be equidivisible if distinct factorizations of an element have always a common refinement. Groups and free semigroups are examples of equidivisible semigroups.We give a complete characterization of pseudovarieties of semigroups whose finitely generated relatively free...

##### The p-median on disconnected graphs
2016-11-09
Speaker: Jorge Orestes Cerdeira (Univ. Nova de Lisboa)
The <i>p</i>-median problem is a well-known NP-hard combinatorial optimization problem that seeks for the location of p facilities on the vertices (customers) of a graph G to minimize the sum of transportation costs for satisfying the demands of the customers from the...

##### The embeddings of Jawerth and Franke for Besov and Triebel-Lizorkin spaces with variable exponents
2016-11-04
Speaker: Helena Gonçalves (Technische Univ. Chemnitz, Germany)
See the attached file...

##### A successful pair: symbolic dynamics and (pro)finite semigroups
2016-11-04
Speaker: Alfredo Costa (CMUC, Univ. Coimbra)
My research has been mostly about exploring natural links between the field of symbolic dynamics and the theory of finite and profinite semigroups, with applications in both directions. The aim of this talk is to give examples of relevant results and open problems stemming from this line of...

##### Ring theoretical and combinatorial aspects of representation theory
2016-11-04
Speaker: Samuel Lopes (CMUP, Univ. Porto)
I will discuss some of my research interests in relation to representation theory of infinite dimensional algebras, highlighting the interplay with topics in ring theory and combinatorics....

##### Diverse paths in network optimisation
2016-10-28
Speaker: Marta Pascoal (Univ. Coimbra)
A path in a graph is a sequence of vertices linked by graph edges. The determination of an optimal path with respect to a given objective function has led to classical network optimization problems. However, for many applications, it is useful to know an alternative backup solution,which can...

##### Positive semidefinite rank and representations of polytopes
2016-10-28
Speaker: João Gouveia (CMUC, Univ. Coimbra)
Let M be a p-by-q matrix with nonnegative entries. The positive semidefinite rank (psd rank) of M is the smallest integer k for which there exist positive semidefinite matrices A_i,B_j of size k×k such that M_{ij}=trace(A_i,B_j). The psd rank was recently introduced, and has has ...

##### Transverse measures and densities for Lie groupoids
2016-10-26
Speaker: João Nuno Mestre (CMUC, Univ. Coimbra)
We explain how extending Haefliger's approach to transverse measures for foliations to general Lie groupoids allows us to define and study measures and geometric measures (densities) on differentiable stacks. The abstract theory works for any differentiable stack, but it becomes very...

##### The deficiency of categories
2016-10-25
Speaker: Fernando Lucatelli Nunes (CMUC)
The study of the deficiency of a category arises from the problem of understanding what is a presentation of a category with the least number of equations and, therefore, avoiding redundancy.I have been studying deficiency within the context of descent and lifting of biadjoints (within the...

##### Implementing a stable version of the tau method in a toolbox
2016-10-19
Speaker: José Matos (ISEP)
The Lanczos' tau method is a spectral method originally proposed to solve linear differential problems with polynomial coefficients. Generalizations to extending its domain of application to integro-differential, nonlinear and functional-differential problems, among others, have been made....

##### Explicit Schoen Surfaces
2016-10-19
Speaker: Carlos Rito (Centro de Matemática da Universidade do Porto)
See the attached file....

##### Group theory and special functions theory: a two way street
2016-10-19
Speaker: R. Álvarez-Nodarse (Univ. Sevilla, Spain)
It is well known the role of symmetries in Science and, particular, in the Physical Sciences. Almost all physical laws are consequence of symmetries. Take as an example the conservation laws of Classical Mechanics and the Noether's theorem. Another interesting example is related to...

##### Reconstruction of complex-valued once differentiable conductivities in 2D
2016-10-14
Speaker: Evgeny Lakshtanov (Univ. Aveiro)
The classical dbar-method has been generalized recently by Lakshtanov, Novikov, Vainberg to be used in the presence of exceptional points. We apply this generalization to solve Dirac inverse scattering problem without assumptions on smoothness of potentials. As a consequence, this provides...

##### A fractional diffusion model with resetting
2016-10-14
Speaker: Ercília Sousa (CMUC, Univ. Coimbra)
We consider a fractional partial differential equation that describes the diffusive motion of a particle, performing a random walk with Lévy distributed jump lengths, on one dimension with an initial position x0. The particle is additionally subject to a resetting dynamics, whereby...

##### Image processing using nonlinear partial differential equations
2016-10-14
Speaker: Sílvia Barbeiro (CMUC, Univ. Coimbra)
When assigned with the task of image reconstruction, the first challenge one faces is the derivation of a truthful model for both the information we want to extract and the data. The natural question arises: how can we make our model adaptive to the given data? Diffusion processes are...

##### The extension operator in variable exponent function spaces
2016-10-12
Speaker: Henning Kempka (Technische Univ. Chemnitz, Germany)
The abstract is in the attached pdf file...

##### First degree cohomology of Specht modules and extensions of symmetric powers
2016-10-12
Speaker: Stephen Donkin (Univ. of York, UK)
This is joint work with H. Geranios. We compute the dimensions of the first degree cohomology of all Specht modules for symmetric groups in characteristic different from 2. Our method is to make a comparison with extension groups for general linear groups and Borel subgroups and then make a...

##### Stochastic dynamics on point processes
2016-09-30
Speaker: Antonio Sodre (Department of Mathematics, Univ. of Texas at Austin)
Deterministic dynamics on stationary point process in R^d are built upon compatible point-shifts:  translation invariant mappings from each point of the process to another. When a point-shift is applied multiple times to a point-process it creates a sequence of distributions, namely,...

##### Saturated numerical semigroups
2016-09-28
Speaker: Manuel B. Branco (Univ. Évora)
See the attached file....

##### The variable coefficients thin obstacle problem
2016-09-23
Speaker: Wenhui Shi (CMUC)
See the attached file....

##### On a fractional Monge-Ampère operator
2016-09-16
Speaker: Fernando Charro (UPC, Barcelona, Spain)
See the attached file. ...

##### Conjecture of Alon-Tarsi
2016-07-20
Speaker: Carlos Gamas (Univ. Coimbra)
See the attached file...

##### Monochromatic configurations in finite colorings of N
2016-07-06
Speaker: Joel Moreira (Ohio State Univ., USA)
Is it possible to color the natural numbers with finitely many colors, so that whenever x and y are of the same color, their sum x+y has a different color? A 1916 theorem of I. Schur tells us that the answer is *no*. In other words, for any finite coloring of N, there exist x and y such that...

##### A preaction of the 0-Hecke monoid
2016-06-29
Speaker: Ana Paula Santana (CMUC, Univ. Coimbra)
I will construct a preaction of the Hecke monoid on the category of rational modules for the quantum negative Borel subgroup of the quantum general linear group. I will also show that this preaction induces a preaction on the category of modules for the quantised Borel-Schur algebra. This...

##### Homotopy Excision
2016-06-28
Speaker: Fernando Lucatelli Nunes (UC student)
Eilenberg and Steenrod proved that ordinary homology is characterized by five axioms. Later, Atiyah, Hirzebruch and Whitehead observed that there are other families of functors that satisfy the four "most important" axioms. They defined the so called "generalized homology...

##### Homological Algebra
2016-06-28
Speaker: Artur de Araujo (UP student)
We will explain the basic concepts of Homological Algebra (Cech cohomology, injective/projective resolutions, derived functors,) and show why, useful as they are, they have shortcomings for a general theory of cohomology. Time allowing, we'll give a hint of why derived categories make up for...

##### Semigroup of endomorphisms of a vector space
2016-06-27
Speaker: A. R. Rajan (Univ. Kerala, India)
The semigroup of endomorphisms of a finite dimensional vector space is an extensively studied object in semigroup theory. Often it is identified with the semigroup M_n(K) of n × n matrices over a field K. As a ring M_n(K) is a basic ring used in structure theory of rings. Hence the...

##### Cross-connections of balanced categories
2016-06-27
Speaker:

P. G. Romeo (Cochin Univ., India)

In this talk I will explain what a balanced category is and show that the ideal categories of a concordant semigroup are balanced categories. I will also mention about the cross-connection of such categories.An extended abstract of the talk is attached herewith....

##### Application of the Kalman filter in the statistical modelling of time series
2016-06-17
Speaker: Marco Costa (ESTGA & CIDMA, Univ. Aveiro)
The Kalman Filter (KF), initially submitted by the Hungarian Rudolf E. Kalman in the context of control problems, has been widely applied in statistical modelling of stochastic processes that allow a state space representation. The success of the KF is attributed to the optimal estimators...

##### On Laguerre-Hahn orthogonal polynomials of class one
2016-06-17
Speaker: Maria das Neves Rebocho (Univ. Beira Interior & CMUC)
We study recurrences for Laguerre–Hahn orthogonal polynomials of class one. It is shown for some families of such Laguerre–Hahn polynomials that the coefficients of the three term recurrence relation satisfy some forms of discrete Painlevé equations, namely dPI and...

##### Geometric and numerical methods for optimal control of mechanical systems
2016-06-15
Speaker: Leonardo Colombo (Univ. Michigan, USA)
Under some mild regularity conditions, optimal control problems can be understood as higher-order variational problems. The aim of this talk is to give a general overview on the use of techniques concerning Geometric Mechanics and Geometric Numerical Integration to solve optimal control...

##### Finite difference methods for the reaction-wave-diffusion equation with distributed order in time
2016-06-01
Speaker: Magda Rebelo (CMA/UNL)
https://dl.dropboxusercontent.com/u/15380061/Abstract_MagdaRebelo.pdf...

##### On the works of A. Markov and Stieltjes on monotonicity of zeros
2016-05-27
Speaker: Kenier Castillo (CMUC)
We discuss, in this didactical talk, old and new results on the monotonicity of zeros of polynomials paying special attention to the flexibility and versatility of the works of A. Markov and Stieltjes on the subject....

##### Topological spaces as algebras
2016-05-19
Speaker: Pier Giorgio Basile (UC PhD student)
Monads, or triples, and the algebras they define, proved to be very important in several fields of mathematics. For example, they allow us to see the algebraic nature owned by topological spaces. This fact, for what concerns compact Hausdorff spaces, is known since 1969 (see [4]). By...

##### The LEGO of localic maps
2016-05-17
Speaker: Jorge Picado (CMUC, Univ. Coimbra)
Assembling a localic map f : L → M from localic maps fi : Si → M, i ∈ J, defined on closed resp. open sublocales (J finite in the closed case) follows the same rules as in the classical case. The corresponding classical facts immediately follow from the behavior of preimages...

##### Reflectivity and its logics
2016-05-17
Speaker: Lurdes Sousa (CMUC, IP Viseu)
In previous joint work with  Jirí  Adámek and Manuela Sobral we presented a logic for finitary epimorphisms which can be seen as an extension of Birkhoff's equational logic. In subsequent papers joint with Jirí Adámek and Michel Hébert, we...

##### Sobolev spaces with power weights perturbed by slowly varying functions
2016-05-13
Speaker: Therese Mieth (Friedrich-Schiller-Univ. Jena, Germany)
See the attached file...

##### A model for phase transitions with competing terms
2016-05-12
Speaker: Margarida Baía (IST, Lisboa)
In this work we study, via $\Gamma$-convergence techniques, the asymptotic behaviour of a family of coupled singular perturbations of a non-convex functional of the type $$\int_\Omega f(u(x),\nabla u(x),\rho(x)) \, dx$$ as a variational model to address  two-phase transitions problems...

##### Invariants and Hochschild cohomology of rings of differential operators in one variable
2016-05-04
Speaker: Samuel Lopes (Univ. Porto)
A polynomial h in the variable x determines the derivation h(d/dx) of the polynomial ring F[x] and, together with the multiplication by x operator, it generates a noncommutative algebra A_h whose elements can be written as differential operators on h(d/dx) with coefficients in F[x]. I will...

##### A discrete nonsymmetric variant of the Minkowski Convex Body Theorem
2016-04-27
Speaker: Stanislav Kondratyev (CMUC)
In this talk we discuss a discrete version of the Minkowski Convex Body Theorem for convex integer polygons on the plane. The theorem states that given a sublattice of the integer lattice, any such polygon with sufficiently many vertices contains at least one point of the sublattice. An...

##### Nijenhuis deformation of Gerstenhaber algebra and Poisson Quasi-Nijenhuis algebroids
2016-04-27
The importance of Nijenhuis tensor on the Lie algebra of vector fields on a manifold is not only because of the Newlander-Nirenberg theorem, but also it appears in the study of Hamiltonian systems. The notion is known for some geometric structures such as Poisson manifolds, Courant...

##### Gradient estimates for the porous medium equation
2016-04-22
Speaker: Juhana Siljander (Univ. Jyväskylä, Finland)
The sharp regularity of weak solutions to the porous medium equation is a long-standing open problem. The fundamental solution of the problem, the so called Barenblatt solution, is known to be C^{1/(m-1)}-Hölder continuous, and it is a natural question whether this is the worst possible...

##### Biology and Mathematics: a strategic alliance against cancer through new anti-tumoral therapies
2016-04-20
Speaker: Emanuela Signori (Univ. Rome, Italy)
Cancer remains one of the leading causes of death globally, affecting both sexes equally with an estimated 12.7 million cases around the world. This number is expected to increase to 21million by 2030, despite several curative strategies are offered to the patients. Therefore, new and...

##### Mixed-Effect State Space models applied to environmental data: the discrimination of the Water Quality Monitoring Sites in River Vouga
2016-04-15
Speaker: Magda Monteiro (ESTGA & CIDMA, Univ. Aveiro)
The surface water quality monitoring is an important concern of public organizations due to its relevance for public health. Statistical methods are taken as consistent and essential tools in the monitoring procedures in order to prevent and identify environmental problems. This work...

##### Numerical investigations of spatially segregation models
2016-04-13
Speaker: Farid Bozorgnia (IST, Univ. Lisboa)
In this talk, we consider different models of Reaction-Diffusion system which describe the interactions between biological components. Thesemodels are:Adjacent segregation: The adjacent segregation model has been studied extensively [2]. In this model particles annihilate on contact, and...

##### An overview over conjugacy in semigroups
2016-04-13
Speaker: António Malheiro (Univ. Nova de Lisboa, CMA)
When generalizing a concept, it is sometimes tempting to think that there should be one correct, or even preferred, generalization. Since semigroup theory is a vast subject, intersecting many areas of pure and applied mathematics, it is probably not reasonable to expect a one-size-fits-all...

##### On topological semi-abelian algebras
2016-04-07
Speaker: Mathieu Duckerts-Antoine (CMUC)
In this talk, we will study some aspects of the categories of topological semi-abelian algebras. In particular, I will explain why these categories are homological. If the time allows it, I will also explain what is a torsion theory in a homological category and give several examples in the...

##### Multiplicity lists for symmetric matrices whose graphs have many edges
2016-04-06
Speaker: Zhang Yulin (Univ. Minho)
We characterize the possible lists of multiplicities occurring among the eigenvalues of real symmetric (or Hermitian) matrices whose graph is one of Kn, Kn less an edge, or both possibilities for Kn less two edges. The lists are quite different from those for trees. Some construction...

##### Banach Frames and Banach Gelfand Triples, with applications to Time-Frequency Analysis
2016-04-06
Speaker: Hans G. Feichtinger (Univ. Vienna, Austria)
It is the purpose of this talk to discuss essentially two concepts which arose in the context of time-frequency analysis (specifically relevant for Gabor Analysis), but which represent useful and fundamental functional analytic tools which certainly will be very useful also in quite...

##### Some results in the context of structured deformations
2016-04-01
Speaker: José Matias (IST, Lisboa)
Structured deformations provide a model to non-classical deformations of continua suitable for the description of deformations of materials whose kinematics requires analysis at both the macroscopic and microscopic levels. We present an overview of the theory and discuss different...

##### BV Formality
2016-03-30
Speaker:

Ricardo Campos (Univ. Zurich, Switzerland)

To a smooth manifold one can associate the Lie algebras of multivectorfields and multidifferential operators. Relating these two led Kontsevich to his famous formality theorem that establishes the deformation quantization of Poisson manifolds.In this talk we will see that if the...

##### Higher centrality via degenerate simplices
2016-03-22
Speaker: Tim Van der Linden (Univ. Catholique de Louvain, Belgium)
When, in a semi-abelian category, a truncated simplicial object is considered as a higher extension, the commutators involved in the centrality condition for this extension may be expressed in terms of degenerate simplices. The aim of my talk is to explain some of the simplicial-geometrical...

##### The Beck-Chevalley property for Goursat categories
2016-03-22
Speaker: Diana Rodelo (CMUC, Univ. Algarve)
We characterise regular Goursat categories through a specific stability property of regular epimorphisms with respect to pullbacks. Under the assumption of the existence of some pushouts this property can be also expressed as a restricted Beck-Chevalley condition, with respect to the...

##### The k-word problem over DRG
2016-03-10
Speaker: Célia Borlido (UPorto student)
The study of finite semigroups has its roots in Theoretical Computer Science. In particular, in the mid nineteen seventies, Eilenberg [2] established the link between "varieties of rational languages", which is an important object of study in Computer Science, and certain classes...

##### n-Algebras admitting a multiplicative basis
2016-03-09
Speaker: José M. Sánchez Delgado (CMUC)
See the attached file....

##### Singular foliations and Lie-infinity algebroids
2016-03-04
Speaker: Camille Laurent-Gengoux (Univ. Lorraine, France)
We will describe a natural L-infinity structure associated to a singular foliation, and explain why they give the geometry of the foliation, like its monodromy. We shall relate this to several classical constructions using Lie groupoids or bisubmersions. Joint work with Sylvain Lavau and...

##### On convolution type operator with piecewise continuous symbols on variable Lebesgue spaces
2016-02-26
Speaker: Oleksiy Karlovych (Univ. Nova de Lisboa)
See the attached file. ...

##### Non-smooth atomic decomposition of 2-microlocal spaces with variable integrability
2016-02-19
Speaker: Helena Gonçalves (Technische Univ. Chemnitz, Germany)
The abstract is in the attached pdf file...

##### Besov and Triebel-Lizorkin spaces with variable exponents
2016-02-18
Speaker: Helena Gonçalves (Technische Univ. Chemnitz, Germany)
See the attached file. Helena Gonçalves is working as a Research Assistant at Chemnitz University of Technology, Germany in the area of "Analysis" under the supervision of Prof. Henning Kempka.The seminar takes place in PORTO. ...

##### Geometry of numerical range of linear pencils
2016-02-17
Speaker: Fatemeh Esmaeili Taheri (CMUC)
See the attached file....

##### On a version of homological algebra in the category of semimodules and its applications
2016-02-16
Speaker: Alex Patchkoria (A. Razmadze Math. Institute of Tbilisi State Univ., Georgia)
We develop a version of homological algebra for semimodules which enables us to: (1) introduce new cohomology monoids of an arbitrary monoid M with coefficients in semimodules over M as more computable alternatives to the old ones, (2) construct singular ...

##### On mixed and stabilized finite element methods for the obstacle problem
2016-02-12
Speaker: Juha Videman (IST, Univ. Lisboa)
The abstract is in the attached pdf file...

##### Systems of PDEs in porous media
2016-02-05
Speaker: Léonard Monsaingeon (IST, Lisboa)
In this talk I will investigate systems of parabolic PDEs in porous media, describing competitive adsorption phenomena in groundwater contaminant models. The system is degenerate and does not fall into the general class of models studied by Alt and Luckhaus, mainly due to the non-convex...

##### The action of a 2-group on a category and its application in higher gauge theory
2016-02-01
Speaker: Roger Picken (IST, Univ. Lisboa)
The fundamental notion of symmetry can be expressed as the action of a group on a set, or more generally in terms of a transformation groupoid. In this talk I will show how a group action on a set may be generalized to a 2-group action on a category C, and how such an action gives rise to a...

##### Howson's property for semidirect products of semilattices by groups
2016-02-01
Speaker: Filipa Soares de Almeida (CEMAT and ISEL, Lisboa)
Howson's Theorem (1954), a classical result in group theory, established that the intersection of two finitely generated subgroups of a free group always yields a finitely generated subgroup. Jones and Trotter (1989) showed that is not the case for any free inverse semigroup with more than...

##### The spectral inclusion regions of linear pencils and numerical range
2016-01-28
Speaker: Fatemeh Esmaeili Taheri (CMUC)
Let A,B be n×n (complex) matrices. We are mainly interested in the study of the structure of the spectrum of a linear pencil, that is, a pencil of the form A−λB, where λ is a complex number. Our main purpose is to obtain spectral inclusion regions for the pencil...

##### Toric constructions of monotone Lagrangian submanifolds in CP^2 and CP^1 x CP^1
2016-01-27
In a previous paper, I proved that two very different constructions of monotone Lagrangian tori are Hamiltonian isotopic inside $\mathbb{CP}^2$ by comparing both of them to a third one called modified Chekanov torus. This modified Chekanov torus has an interesting projection under the...

##### Computational modeling of hematopoietic stem/progenitor cells expansion and differentiation
2016-01-20
Quantifying the effect of exogenous parameters regulating hematopoietic stem/progenitor cells (HSC/HPC) expansion and differentiation will enhance to design robust and efficient protocols to be used for cell‐based therapies. Herein, a computational model was developed that...

##### The Universal Generalization Problem. Euclid's mathematical solutions and contemporary formal accounts
2016-01-18
Speaker:

Pierluigi Graziani (University of Chieti-Pescara - Italy)

The goal of my talk is to analyze different contemporary foundations of Euclid's Geometry [1], compare them with each other and with the philological studies of ancient texts. In particular, I will analyze how these foundational studies fare with respect to the Universal Generalization...

##### The poset of proper divisibility
2016-01-18
Speaker: Antonio Macchia (CMUC)
Inspired by the definition of the Buchberger graph of a monomial ideal, we study proper divisibility of monomials as a partial order in N^n, from a combinatorial and topological point of view. From this order relation we obtain a new family of posets, that we call posets of proper...

##### Exponential splitting methods for the time integration of the Klein-Gordon equation with Hagstrom-Warburton high-order absorbing boundary conditions
2016-01-18
Speaker: Ana M. Portillo (Univ. Valladolid, Spain)
Klein-Gordon equations on an unbounded domain are considered in one dimensional and two dimensional cases. Numerical computation is reduced to a finite domain by using the Hagstrom-Warburton high-order absorbing boundary conditions. The space discretization is reached by means of finite...

##### An overview on the dimension of projected patterns in reaction-diffusion systems
2015-12-17
Speaker: Juliane Fonseca de Oliveira (UPorto student)
TBA...

##### Tuning polymeric and drug properties in a drug-eluting stent: a numerical study
2015-12-17
Speaker: Jahed Naghipoor (ISM, Bauhaus-Universität Weimar, Germany)
TBA...

##### Change of matrix eigenvalues multiplicity associated with perturbation of a diagonal element or deletion of a row and column
2015-12-16
Speaker: Antonio Leal Duarte (CMUC, Univ. Coimbra)
Given an nxn matrix A, an eigenvalue λ of A and an index i (1\le i \le n) we say that i is downer (respectively neutral or Parter), if the multiplicity of λ in the matrix A(i) (obtained from A by deleting row and column i is smaller (resp equal or greater) than the...

##### Homotopy theory of 2-categories
2015-12-15
Speaker: Benjamín Alarcón Heredia (CMA, FCT-UNL)
The category of small categories has a Thomason model structure making its homotopy category equivalent to the classical homotopy category of topological spaces. The same is true for small 2-categories, so we can think of small 2-categories as spaces. In this talk I will present the...

##### The rank of variants of nilpotent pseudovarieties
2015-12-15
Speaker:

M. Hossein Shahzamanian C. (CMUP, Univ. Porto)

In this talk, we investigate the rank of classes defined by several of the variants of nilpotent semigroups in the sense of Mal'cev. For several of them, we even give finite basis of pseudoidentities. We show that the pseudovariety $\mathsf{NT}$ has infinite rank and, therefore, it is...

##### From medical images to computational hemodynamics: a robust pipeline
2015-12-09
Speaker: Ana J. João (CEMAT-IST, ULisboa)
In the past decade, with the proliferation of technology and the increase of its capability, Computational Fluid Dynamics (CFD) has become a popular tool in several applications. This combined with our desire of increasing human life expectancy has lead to the combination of CFD and...

##### The electrostatic limit for the Zakharov system
2015-11-19
Speaker: Luigi Forcella (Scuola Normale Superiore di Pisa, Italy)
The Zakharov system describes the coupled dynamics of the electric field amplitude and the low frequency fluctuation of the ions in a unmagnetized or weakly magnetized plasma. This system couples Schrödinger-like and wave equations and in its physical derivation depends on a parameter...

##### Analogies between optimal transport and minimal entropy
2015-11-19
Speaker: Luigia Ripani (Univ. Claude Bernard Lyon 1, France)
The Schrödinger problem is an entropic minimization problem and it's a regular approximation of the Monge-Kantorovich problem, at the core of the Optimal Transport theory.In this talk I will first introduce the two problems, then I will describe some analogy between optimal transport...

##### Relaxation in BV×Lp
2015-11-13
Speaker: Graça Carita (Univ. Évora)
An integral representation result is obtained for the relaxation of a class of energy functionals depending on two vector fields u in BV and v in Lp with 1<p≤+∞. This energy have been introduced to deal with equilibria for systems depending on...

##### The Taylor property in non-negative autoregressive stochastic processes
2015-11-13
Speaker: Cristina Martins (DMUC, Univ. Coimbra)
In this talk we analyse the presence of the Taylor property in linear models. Limiting the study to non-negative models, we begin by recalling the main theoretical results on the occurrence of the Taylor property in autoregressive models of order one. These results are discussed in models...

##### What is Nelson's admissibility condition?
2015-11-10
Speaker: Tim Van der Linden (Université Catholique de Louvain, Belgium)
In his Ph.D.thesis [3], Nelson Martins-Ferreira introduced a technical condition (for a certain type of diagram in a category) which he called admissibility. His first aim was to efficiently describe internal categorical structures, but the flexibility of the condition allowed him to use it...

##### A characterization of central extensions in the variety of quandles
2015-11-10
Speaker: Andrea Montoli (CMUC, Univ. Coimbra)
The category of symmetric quandles is a Mal'tsev variety whose subvariety of abelian symmetric quandles is the category of abelian algebras. We give an algebraic description of the quandle extensions that are central for the adjunction between the variety of quandles and its subvariety of...

##### A numerical solution for a governing equation of Lévy motion
2015-11-04
Speaker: Ercília Sousa (CMUC, Univ. Coimbra)
This study looks at a governing equation of Lévy motion. This governing equation is a generalization of the classical, deterministic advection diffusion equation, just as Lévy motion is a generalization of Brownian motion. It can be represented by fractional derivatives, which...

##### A tropical approach to stable spin curves
2015-11-04
Speaker: Ana Margarida Melo (CMUC, Univ. Coimbra)
The moduli space of spin curves of genus $g$ parametrizes pairs consisting of a curve and a square root of the canonical class on the curve. It is therefore endowed with a forgetful map to $M_g$, the moduli space of curves of genus $g$, which has degree $2^{2g}$. There are different modular...

##### Groupoids, fibrations and rigidity
2015-10-28
Speaker: Matias del Hoyo (IMPA, Brazil)
Fibred categories were introduced in descent theory by A. Grothendieck. In this talk I will discuss fibred Lie groupoids, an incarnation of that formalism in differential geometry, studied by K. Mackenzie, among others. In a joint work with R. Fernandes we construct suitable metrics on...

##### On pseudovarieties of forest algebras
2015-10-27
Forest algebras are used in the theory of formal languages. They consist of two monoids, the horizontal one H and the vertical one V , with an action of V on H, and a complementary axiom of faithfulness. The main example is the forest algebras of plane forests and contexts, that is to say...

##### A distance on the space of Radon measures with application to spatial population dynamics
2015-10-23
Speaker: Stanislav Kondratyev (CMUC, Univ. Coimbra)
We introduce a new optimal transport distance between nonnegative finite Radon measures, derive associated Riemannian structure and develop an Otto calculus.  As an application, we identify a model in spatial population dynamics as a gradient flow and obtain long-time convergence...

##### Rolling maps and applications
2015-10-22
Speaker: Fátima Pina
Rolling motions are rigid motions subject to holonomic and nonholonomic constraints. These motions appear associated to certain engineering areas, such as robotics and computer vision. Rolling maps are the mathematical tools to describe rolling motions.In this talk, the concept of rolling...

##### Invariant factors of matrices over general rings
2015-10-14
Speaker: Joao Filipe Queiró (CMUC, Univ. Coimbra)
This talk is a report on recent work with Cristina Caldeira concerning invariant factors of products of matrices over the class of elementary divisor domains. For an nxn matrix over such a ring R, and a pure submodule of R^n, we define a new type of "Rayleigh functional" and use...

##### Biadjoint triangles, descent and coherence
2015-10-13
Speaker: Fernando Lucatelli Nunes (CMUC, Univ. Coimbra)
Firstly, we talk about the general result of coherence due to Power-Kelly-Blackwell and Lack. Then, we show how this motivates the study of a 2-dimensional version of Eduardo Dubuc's adjoint triangle theorem.At last, we show what the proofs of the (bi)adjoint triangle theorems have to do...

##### Functional representations of monads in duality theory
2015-10-13
Speaker: Pedro Nora (Univ. Aveiro)
It is well known that Stone's classical duality theorems can be generalised to categories of spaces and continuous relations. For example, Halmos's duality theorem affirms that the category of Stone spaces and Boolean relations (relations which are continuous in an appropriate sense) is...

##### A coupled release-absorption model for drug delivery systems
2015-10-07
Speaker:
Giuseppe Pontrelli (Istitupo per le Applicazioni del Calcolo, Rome, Italy)
In this talk I will present a mathematical model describing the release from a drug delivery system, such as a coronary eluting stent or a transdermal patch.The problem is reduced to a dynamics of a two-phase substance between two coupled  media of different properties and extents. The...

##### Approximation numbers of weighted Sobolev embeddings via bracketing
2015-10-02
Speaker: Therese Mieth (Friedrich-Schiller-Univ. Jena, Germany)
...

##### Heegaard genus and rank of link complements
2015-09-30
Speaker: Darlan Girão (Univ. Federal Ceará, Brazil)
In this talk we will discuss the relationship between the Heegaard genus and rank of 3-dimentional manifolds. Despite some recent advances in this topic, little is known for manifolds arising as link complements in S^3. We will provide a very rich class of link complements for which rank...

##### Birationality of moduli spaces of twisted U(p,q)-Higgs bundles
2015-09-29
Let X be a Riemann surface of genus g greater or equal than 2. A twisted U(p,q)-Higgs bundle consists of a pair of holomorphic vector bundles on a Riemann surface, together with a pair of twisted maps between them. Here we study the variation with the parameter of the moduli space of...

##### Numerical solution of time-dependent Maxwell's equations in anisotropic materials for modelling light scattering in human eye's structure
2015-09-24
Speaker: Maryam Khaksar Ghalati
Modelling light propagation in biological tissue has become an important research topic in biomedical optics with application in diverse fields as for example in ophthalmology. Waveguides with induced anisotropy may worth to be modeled as they could play a role in biological waveguides. For...

##### The meet formula for pseudocomplement and an aspect of the coframe of sublocales
2015-09-09
Speaker: Aleš Pultr (Charles Univ., Prague, Czech Republic)
A frame is a complete Heyting algebra; in particular it is pseudocomplemented and we have the formula a^* = \bigvee{x : x \wedge a = 0}. Dually, in a coframe we have the formula for the supplement a^# = \bigwedge{x : x v a = 1}. (#) Somewhat surprisingly, under suitable (and very...

##### Nearly Sasakian manifolds and related structures.
2015-09-08
Speaker: Giulia Dileo (Univ. Bari, Italy)
Nearly Sasakian manifolds are a special class of almost contact metric manifolds, providing a natural odd dimensionalcounterpart of nearly Kähler manifolds.In the present talk I will describe the main properties of nearly Sasakian manifolds, referring also to geometric structures which...

##### On the discriminated nondimensionalization of coupled, non-linear ordinary differential equations and system of equations
2015-07-24
Speaker: Manuel Conesa (Univ. Politécnica de Cartagena, Spain)
The first step to simplify the analysis of a mathematical model is to search the dimensionless groups that control its solution pattern since the solution of any equation or system of equations that define the laws that rule a physical or engineering problem can be represented as a relation...

##### A branching process approach to the survival of populations: skeleton process and stochastic introgression
2015-07-17
Speaker: Maria Conceição Serra (CMAT, Univ. Minho)
In this talk we present branching processes as a tool to model the evolution of populations which are, in principle, doomed to extinction but manage to survive. Survival is usually achieved through the appearance of different types of individuals that give an “advantage” to the...

##### Height functions on symmetric spaces
2015-07-09
Speaker: María José Pereira-Sáez (Univ. Coruña, Spain)
Morse theory gives us useful techniques to analyze the homotopic structure of a smooth manifold studying some smooth functions on this manifold. This allows us to find the cellular structure of a CW-complex and get some information about its cohomology. We will consider here height...

##### Object detection, multispectral fusion, motion analysis and tracking in aerial imagery and video
2015-07-08
Speaker: Kannappan Palaniappan (Univ. Missouri, Columbia, USA)
Visual feature-based tracking systems need to adapt to variations in the appearance of an object and in the scene for robust performance to avoid drift. Tracking in aerial imagery is challenging as viewing geometry, calibration inaccuracies, complex flight paths and back- ground changes...

##### Filtering, fusion, detection and segmentation of microvasculature vessel fluorescence imagery
2015-07-07
Speaker: Kannappan Palaniappan (Univ. Missouri, Columbia, USA)
Automatic segmentation of three-dimensional microvascular structures is needed for quantifying morphological changes and remodeling of blood vessels during development, disease and treatment processes. We use an approach for vessel segmentation that combines multiple single focus images use...

##### Supernilpotent algebras are non-dualizable
2015-07-07
Speaker: Wolfram Bentz (CEMAT-­FCUL, Univ. de Lisboa)
Natural dualities, such as Stone duality, are useful because they allow one to translate algebraic questions into the potentially simpler and usually more intuitive setting of a topological structure. If these dualities exist for particular classes of algebras, then they can be obtained in a...

##### The Karoubi envelope and the Schützenberger category of a semigroup.
2015-07-07
Speaker: Alfredo Costa (CMUC, Univ. Coimbra)
The Karoubi envelope plays a fundamental role in Tilson's Delay theorem, an important result in the theory of pseudovarieties of semigroups. It is also known that two semigroups with local units are Morita equivalent if and only if they have equivalent Karoubi envelops.We introduce a new...

##### On displaceability of pre-Lagrangians in toric contact manifolds
2015-07-02
Speaker: Milena Pabiniak (IST Lisboa)
In symplectic geometry one can observe a rigidity of intersections: certain (Lagrangian) submanifolds are forced to intersect each other in more points than an argument from algebraic or differential topology would predict. For example, every compact symplectic toric manifold contains a...

##### On computing efficient pairs of disjoint paths
2015-07-01
Speaker: Marta Pascoal (INESC / Univ. Coimbra)
Pairs of disjoint paths between two nodes in a network provide a primary path as well as a backup path, such that the latter can be used in case one of the arcs of the first is not available. The problem of finding the shortest pair of disjoint paths can be formulated as a minimum cost flow...

##### Coistropic reduction for Poisson Lie actions
2015-06-18
Speaker: Chiara Esposito (Univ. Wuerzburg, Germany)
In this talk we present a reduction procedure in the setting of a Poisson Lie group (G,\pi_G) acting on a Poisson manifold (M, \pi). In such cases we can introduce the notion of comomentum map and we show that, under certain conditions, it produces a Hamiltonian action on the...

##### Convergence of Kiefer-Wolfowitz algorithm under quasi-associated random errors
2015-06-18
Speaker: Idir Arab (University of Bejaia, Algeria)
In this talk, we study the algorithm of Kiefer-Wolfowitz under quasi-associated random errors. We establish the complete convergence and obtain an exponential bound. Additionally, we build a confidence interval for the minimum. Numerical examples are sketched out to confirm the theoretical...

##### Arbitrary triple systems admitting a multiplicative basis
2015-06-18
Let T be a triple system of arbitrary dimension, over an arbitrary base field K and in which any identity on the triple product is not supposed. A basis of T is called multiplicative if for any three elements we have that its product is a multiple (coefficient in K) of some element of the...

##### Modeling Dengue disease: two real outbreaks - theoretical and practical issues
2015-06-17
Speaker: Maria Teresa Monteiro (ALGORITMI, Univ. Minho)
Epidemiology has become an important issue for modern society. Demographic evolution, accelerated urbanization, increased traveling and climate change, all favor the propagation of infectious diseases.Dengue is the most rapidly spreading mosquito-borne viral disease in the world. According...

##### Regularity properties of maximal functions
2015-06-08
Speaker: Emanuel Carneiro (IMPA, Rio de Janeiro, Brazil)
In this talk I will briefly survey the regularity theory for maximal operators in Sobolev and BV spaces. It has been conjectured for more than a decade that the classical centered one-dimensional Hardy-Littlewood maximal operator should not increase the variation of a function. The...

##### L-infty graded manifolds, Kapranov manifolds and applications
2015-06-05
Speaker: Camille Laurent-Gengoux (Univ. Lorraine, France)
Several linearization problems can be expressed as the linearization of a L-infty algebra for a particular type, that we call Kapranov manifold.A algebroid cohomology class, called the Atiyah class, plays there a crucial role. Joint works with Mathieu Stiénon, Yannick Voglaire and...

##### Quaternion Newton-like methods
2015-06-03
Speaker: Maria Irene Falcão (Univ. Minho)
It is a well known fact that the algebraic as well as the geometric properties of complex holomorphic functions are not the same for their generalizations in quaternion analysis. In particular, because of the non-commutativity of quaternion multiplication, the use of root-finding methods...

##### On Auslander-Reiten sequences for simple modules in the Borel-Schur algebras
2015-06-03
Speaker: Ana Paula Santana (CMUC/Univ. Coimbra)
I will construct Auslander-Reiten sequences for a large class of simple modules over Borel-Schur algebras. Partial information on the structure of the socles of Borel-Schur algebras will also be given.This is joint work with Karin Erdmann and Ivan Yudin....

##### Eigenvalues, multiplicities and graphs: recent advances and open problems
2015-06-01
Speaker: Charles R. Johnson (College of William and Mary, Williamsburg, USA)
Let G be an undirected graph on n vertices and let S(G) denote the set of all symmetric matrices with graph G and let L(G) denote the set of all multiplicity lists occurring among the matrices in S(G). The diagonal entries of matrices in S(G) are free. There has long been study of this...

##### Invariant manifolds of non-autonomous ODEs
2015-05-29
Speaker: António Bento (Univ. Beira Interior)
...

##### Primitive multiple curves: classification, moduli spaces of sheaves, deformations
2015-05-27
Speaker: Jean-Marc Drézet (Institut de mathématiques de Jussieu, France)
A primitive multiple curve is a Cohen-Macaulay irreducible projective curve Y that can be locally embedded in a smooth surface, and such that Yred is smooth. These curves have been defined and studied by C. Banica and O. Forster in 1984.In 1995, D. Bayer and D. Eisenbud gave a complete...

##### Kan-injectivity of locales and spaces
2015-05-19
Speaker: Lurdes Sousa (IP Viseu and CMUC)
Two well-known important facts are the characterization of the continuous lattices as the spaces injective with respect to embeddings in the category Top0 of T0 topological spaces (D. Scott, 1972), and the characterization of the stably locally compact locales as the locales injective with...

##### What is an ideal a zero-class of?
2015-05-19
Speaker: Andrea Montoli (CMUC)
We characterize, in pointed regular categories, the ideals as the zero-classes of surjective relations. Moreover, we study a variation of the ''Smith is Huq'' condition: two surjective left split relations commute as soon as their zero-classes commute.Joint work with Nelson Martins-Ferreira,...

##### Boundedness of Stein's spherical maximal function in variable Lebesgue space and application to the wave equation
2015-05-15
Speaker:

Amiran Gogatishvili (Czech Academy of Sciences, Czech Republic)

The abstract is in the attached pdf file...

##### Wavelets in Economics and Political Science
2015-05-06
Speaker: Maria Joana Soares (Univ. Minho)
The use of wavelet analysis is already very common in a large variety of disciplines, such as physics, geophysics, signal and image processing, medicine, biology, etc. More recently, wavelet tools have also been applied successfully in the areas of economics and finance. In spite of their...

##### Harmonic Analysis for the Natural Sciences II
2015-04-24
Speaker: Luís Daniel Abreu (ARI-Austrian Academy of Sciences)
This is a continuation of Wednesday's talk on the Numerical Analysis seminar. After a short presentation of the program, I will focus on the new approach to the localization problem which is being developed with João M. Pereira, a former student of DMUC....

##### Harmonic Analysis for the Natural Sciences
2015-04-22
Speaker: Luís Daniel Abreu (ARI-Austrian Academy of Sciences)
In the Natural Sciences, researchers are often faced with three problems of significant mathematical complexity. The first problem arises in every science where the observation process plays an important role: the need of restricting their measurements to a subregion of the ambient...

##### Kinetic theory of simple reacting spheres: modelling and hydrodynamic regimes
2015-04-17
Speaker: Ana Jacinta Soares (Univ. Minho)
In the frame of the kinetic theory of chemically reacting gases, we consider the model of simple reacting spheres (SRS) in a moderately dense gas regime. The gas molecules behave as if they were single mass points and collisions result in chemically reactive encounters when the kinetic...

##### Computational hydrodynamics, from theory to practice
2015-04-15
Speaker: José S. Antunes do Carmo (Marine and Environmental Sciences Centre/UC)
In the 80’s, numerical models based on the Saint-Venant equations, or shallow water equations, were frequently used in practical applications. However, as has been widely demonstrated, in shallow water conditions and for some types of waves, models based on a non-dispersive theory, of...

##### Monóides de Ehresmann
2015-04-15
Speaker: Gracinda M.S. Gomes (DM-­FCUL e CEMAT-­FCUL, Univ. Lisboa)
Na teoria dos monóides inversos a classe dos próprios, ou E-­unitários, tem um papel crucial, já que todo o monóide inverso tem uma cobertura própria (que separa idempotentes), um monóide inverso próprio ...

##### Borel-Schur algebras of finite representation type
2015-04-15
Speaker: Ivan Yudin (CMUC)
In my talk I will explain what is the representation type of a finite dimensional algebra. Then I will describe the Borel-Schur algebras of finite type. This is a joint work with K. Erdmann and A.P. Santana....

##### A Néron model of the universal jacobian
2015-04-13
Speaker: David Holmes (Univ. Leiden, The Netherlands)
Every non-singular algebraic curve C has a jacobian J, which is an abelian variety. Choosing a point on the curve determines an abel-jacobi' map from C to J. The same constructions can be made in families: given a family of non-singular curves (together with a section), one obtains a family...

##### An optimal design problem with fractional diffusion
2015-04-10
Speaker: Rafayel Teymurazyan (CMUC)
We study an optimization problem ruled by a-fractional diffusion operator with volume constraint. By means of penalization techniques we prove existence of solutions. We also show that every solution is locally of class C0,\alpha, and that the free boundary is a C1,\alpha surface, up to a...

##### Assessment of image derived PET quantification techniques
2015-04-08
Speaker: Miguel Patrício (Lab. Biostatistics and Medical Informatics, IBILI-FMUC)
Data detected by a positron emission tomography (PET) scanner is translated into concentration of radiotracer by using image reconstruction methods. Applying reconstruction algorithms will only retrieve the radiotracer concentration. However, there will be no discrimination between...

##### The exact discrete Lagrangian function in the Lie groupoid setting
2015-04-08
Speaker: Juan Carlos Marrero (Univ. de La Laguna, Spain)
In this talk, I will present a definition of the exact discrete Lagrangian function associated with a continuous regular Lagrangian function on the Lie algebroid of a Lie groupoid. A result on variational analysis error in this setting will also be presented. In order to define the exact...

##### Rolling pseudo-Riemannian submanifolds
2015-03-25
Speaker: André Marques (Instituto Politécnico de Viseu)
We present an overview about rolling motions, subject to non-slip and non-twist constraints, of manifolds which are embedded in pseudo-Riemannian manifolds. Within this general framework, we analyze the individual cases of rolling of pseudo-hyperbolic spaces and quadratic Lie groups. We...

##### Covers of the projective plane
2015-03-25
Speaker: Eduardo Dias (Univ. Warwick, UK)
The problem of describing the equations of a projective model of an irregular variety is often a difficult one. In this talk we will focus on the case of irregular surfaces. We will describe the construction of the projective model of an Abelian surface with a polarization of type (1,3) via...

##### Peiffer product and Peiffer commutator for internal pre-crossed modules
2015-03-24
Speaker: Alan S. Cigoli (Università degli Studi di Milano, Italy)
In this work we introduce the notions of Peiffer product and Peiffer commutator of internal pre-crossed modules over a fixed object B, extending the corresponding classical notions to any semi-abelian category. We prove that, under mild additional assumptions on the category, crossed modules...

##### The localic group of the unit circle
2015-03-24
Speaker:

Imanol Mozo Carollo (UPV/EHU, Bilbao, Spain)

The category of locales, which is the object of study of pointfree topology, has an algebraic dual, the category of frames. This fact was used by Joyal in order to introduce the frame of reals as a pointfree counterpart of the real line [3]. Further, this lead to a fruitful study of the...

##### Modeling blood flow and mass transport by a drug eluting stent
2015-03-18
Speaker: Elias Gudiño (IST, Lisboa)
In this seminar we will present a fully coupled model for the description of blood flow and mass transport by a drug eluting stent in blood vessels. In order to obtain a numerical solution of the problem, we use an iterative splitting scheme over a stabilized finite element method together...

##### About embeddings and minimal action solutions of elliptic equations
2015-03-13
Speaker: Eugénio Rocha (Univ. Aveiro)
in the attached file ...

##### Invariant theory and descent via symmetric monoidal categories
2015-03-11
Speaker: Ehud Meir (Univ. Copenhagen, Denmark)
Let C be a symmetric monoidal K-linear category, where K is an algebraically closed field of characteristic zero.  Deligne proved that if C satisfies a certain finiteness assumption, then C is necessarily equivalent to the category Rep_K-G, of the finite dimensional rational...

##### Modelling with clinical data: examples, limitations, aims ...
2015-03-11
Speaker: Carla Henriques (CMUC and Instituto Politécnico de Viseu)
In this seminar, we will present some examples of applications of Statistics in the field of Medicine. Research questions are posed by health professionals, who aim to see their "sensibilities" supported statistically. The answers are not always straightforward, and the...

##### Orthogonal polynomial interpretation of \Delta-Toda and Volterra lattices
2015-02-27
Speaker: Ana Foulquié Moreno (Univ. Aveiro)
The correspondence between dynamics of $\Delta$-Toda and $\Delta$-Volterra lattices for the coefficients of the Jacobi operator and its resolvent function is established. A method to solve inverse problem --integration of $\Delta$--Toda and $\Delta$-Volterra lattices -- based on Pad\'e...

##### Plactic, hypoplactic, and Sylvester monoids, and other homogeneous monoids
2015-02-25
Speaker: Alan Cain (CMA, Univ. Nova de Lisboa)
In recent work with Gray and Malheiro, I proved that finite-rank plactic monoids (in which Young tableaux form a cross-section) admit finite convergent presentations and are biautomatic. This seminar will survey three themes arising from this work: (1) Using similar techniques with rather...

##### Sasakian nilmanifolds
2015-02-19
Speaker: Antonio De Nicola (CMUC, Univ. Coimbra)
Sullivan's theory of models can be used to get topological invariants of manifolds that are stronger than the de Rham cohomology ring.One defines a model for a manifold as a commutative differential graded algebra (CDGA) quasi-isomorphic to the algebra of differential forms. It is known that...

##### Some recent mathematical ideas for applications in biology
2015-02-11
Speaker: Ezio Venturino (Univ. Torino, Italy)
In this talk classical models in ecology and epidemiology will be presented and reviewed. These two fields have grown independently for a long time. Scientists have treated them separately, but only fairly recently have begun to realize that they do influence one another profoundly. Some...

##### A Wasserstein gradient flow approach to Poisson-Nernst-Planck equations
2015-02-06
Speaker: Léonard Monsaingeon (IST, Univ. Lisboa)
The abstract is in the attached pdf file...

2015-02-04
A new spectral graph invariant spr(R), called Randic spread, is defined and investigated. This quantity is equal to the maximal difference between two eigenvalues of the Randic matrix, disregarding the spectral radius. Lower bounds for spr(R) are deduced, some of which depending on the Randi...

##### Modeling and analysis of count data time series: recent research activities
2015-02-03
Speaker: Christian H. Weiß (Helmut Schmidt Univ. Hamburg, Germany)
After a brief introduction to basic concepts and examples of count data time series, we shall focus on two particular models and their statistical analysis: the (compound) Poisson INAR(1) model and the (self-exciting threshold) binomial AR(1) model.The Poisson INAR(1) model is the most...

##### Hexagonal projected symmetries
2015-01-28
Speaker: Juliane Oliveira (Univ. Porto)
Three-dimensional symmetries are often observed as 2-dimensional objects. In this seminar we will provide a description of which 3-dimensional lattices may produce 2-dimensional projected pattern with hexagonal symmetries. As an application we compare some projected spatially periodic...

##### Compactness in quasi-Banach function spaces
2015-01-23
Speaker: António Caetano (Univ. Aveiro)
The well-known criterion for the precompactness of sets in a Banach function space states that a subset K of the absolutely continuous part Xa of a Banach function space X is precompact in X if and only if K is locally precompact in measure and K has uniformly absolutely...

##### From ordered to metric compact Hausdorff spaces
2015-01-13
Speaker: Dirk Hofmann (Univ. Aveiro)
The aim of this talk is to lift the well-known equivalence between ordered compact Hausdorff spaces and stably compact spaces to the metric world, together with several constructions involving these types of spaces....

##### On the "Smith is Huq" condition in S-protomodular categories
2015-01-13
Speaker: Andrea Montoli (CMUC)
We study the so-called "Smith is Huq" condition in the context of S-protomodular categories: two S-equivalence relations centralise each other if and only if their normalisations commute. We prove that this condition is satisfied by every category of monoids with operations...

##### Numerical modeling of complex fluid flows using the Finite Volume Method
2014-12-10
Speaker: Luís Ferrás (Inst. Polímeros e Compósitos, Univ. do Minho)
In this work we present a study on flows of Newtonian and Non-Newtonian fluids, carried out both analytically and numerically. Industrial applications of these flows are found in classical industries such as in polymer processing (for instance in extrusion) and in more modern applications as...

##### Density-based cluster analysis: an interface between Statistics, Differential Topology and Dynamical Systems
2014-12-10
Speaker: José E. Chacón (Univ. de Extremadura, Spain)
Despite its popularity, the investigation of some theoretical aspects of clustering has been relatively sparse. One of the main reasons for this lack of theoretical results is surely the fact that, unlike the situation with other statistical problems as regression or classification, for some...

##### Monoid theoretic approach to bicategorical structures
2014-12-09
Speaker: Dimitri Chikhladze (CMUC, Univ. Coimbra)
We develop a lax version of the formal theory of monads, and consider its connection with the bicategorical structures and the theory of generalized operads. ...

##### Kaehler-Lie systems and geometric quantum mechanics
2014-12-04
Speaker: Jesús Clemente-Gallardo (Univ. Zaragoza, Spain)
In this seminar we will study an application of the geometric formulation of Quantum Mechanics to study Lie systems on finite-dimensional complex manifolds. We will present the geometric methods developed to study their superposition rules, time independent constants of motion, Lie...

##### Orthogonal polynomials and random matrices
2014-11-28
Speaker: Alfredo Deaño (Univ. Carlos III, Madrid, Spain)
In this talk we present some classical results on unitarily invariant ensembles of random matrices of size NxN, the prime example being the Gaussian Unitary Ensemble (GUE). It will be shown how the analysis of the corresponding family of orthogonal polynomials on the real line can be used...

##### Quasi-F frames
2014-11-25
Speaker: Mack Matlabyana (Univ. Limpopo, South Africa)
A completely regular frame L is said to be quasi-F if for every dense c ∈ CozL, the open quotient L →↓a is a C*-quotient map.Quasi-F frames generalize almost-P frames and F'-frames. The intention of the talk is to give several characterizations of these frames....

##### On topological semi-abelian algebras: split extensions and their classifiers
2014-11-25
Speaker: Maria Manuel Clementino (CMUC, Univ. Coimbra)
Actions of a group B on a group X correspond bijectively to split extensions of B with kernel X, or to semidirect products of X and B, or to group homomorphisms from B to the group Aut(X) of automorphisms of X. This last property of Aut(X) is usually identified as representability of...

##### Bi-periodic solutions to the Fokker-Planck equation and operation of Brownian motors
2014-11-21
Speaker: Dmitry Vorotnikov (CMUC, Univ. Coimbra)
We study the unidirectional transport effect for Brownian ratchets modeled by Fokker--Planck-type equations. In particular, we consider the adiabatic andsemiadiabatic limits for tilting ratchets, generic ratchets with small diffusion, and the multi-state chemical ratchets. Having...

##### Hypermaps and their classifications
2014-11-19
Speaker: Domenico Antonino Catalano (Univ. Aveiro)
Problems in hypermap theory have applications to many branches of mathematics. This is a consequence of the different interpretations of the notion of a hypermap. A hypermap is-A representation of a hypergraph (Combinatorics);-A triangulation of a compact surface (Topology);-A quotient of an...

##### Split Lie algebras and relations with weight modules
2014-11-19
Speaker: José M. Sánchez Delgado (Univ. Cádiz, Spain)
We begin by reviewing the main results of the theory of finite dimensional Lie algebras. We continue by considering the class of split Lie algebras of arbitrary dimension. As a generalization, we study the structure of weight modules over< split Lie algebras.We show that under certain...

##### Random fields and random sampling
2014-11-14
Speaker: Maria da Graça Temido (CMUC, Univ. Coimbra)
This talk is focused on the study of the maximum term of a stationary bivariate random field. Considering the double random dimensions with asymptotic geometric growing pattern, in probability, a mixture distribution for the maximum is established. ...

##### Connected components of character varieties and Higgs bundles
2014-11-12
Given a compact Riemann surface X and a real reductive Lie group G, let  R_G=Hom^{red}(\pi_1 X,G)/G be the space of reductive representations of \pi_1 X in G, the so-called G-character variety of X. This is a space with a very rich topological structure, reflecting the topology of both...

##### Constrained optimization techniques for quadratic matrix model updating
2014-11-12
Speaker:

Marcos Raydan (Univ. Simón Bolívar, Venezuela)

The Quadratic Finite Element Model Updating Problem (QFEMUP) concerns with updating a symmetric second-order finite element model so that it remains symmetric and the updated model reproduces a given set of desired eigenvalues and eigenvectors by replacing the corresponding ones from...

##### Noncrossing partitions in negative CY triangulated categories
2014-11-05
Speaker: Raquel Coelho Guardado Simões (Univ. Lisboa)
A key way to understand triangulated categories is to look at generators. In the context of positive Calabi-Yau (CY) triangulated categories, such as cluster categories, the most interesting generators seem to be cluster-tilting objects. There are some triangulated categories which are...

##### Extreme Value Theory for chaotic dynamics
2014-10-31
Speaker: Jorge Milhazes Freitas (CMUP, Univ. Porto)
We will give an introduction to the Extreme Value Theory in a dynamical systems context. In particular, we will interpret the occurrence of rare events in terms of the hitting time to certain shrinking targets on the phase space of the possible states of a given system. We will present new...

##### Involutive double categories
2014-10-28
Speaker: Rachel A.D. Martins (IST/UL)
A double category has an equivalent description as a double partial monoid, that is, a set equipped with two partial monoid structures such that all structure maps are partial monoid homomorphisms. Double categories can have an interesting and natural involutive structure, which we ...

##### Some remarks on descent for Priestley spaces
2014-10-28
Speaker: Manuela Sobral (CMUC, Univ. Coimbra)
In this talk the problem of characterizing effective descent morphisms for Priestley spaces is recalled and solved in two veryspecial cases: for maps with finite codomain and for maps that are open and order-open, or, equivalently, open and order-closed....

##### Uniform convergence of Hermite-Padé approximants for systems of Markov type functions
2014-10-24
Speaker: Sergio Medina Peralta (Univ. Carlos III, Madrid, Spain)
This talk deals with simultaneous rational approximation. In particular we study Hermite-Padé approximants of analytic and meromorphic functions of Markov type. The central results of this work is about of convergence of type I Hermite-Padé approximants of a Nikishin system....

##### The MOOD method, principle and (some) examples
2014-10-15
Speaker: Stéphane Clain (Univ. Minho)
We present a new finite volume method to provide 6th-order approximations for hyperbolic problems.The technique is based on the one hand to a conservative polynomial reconstruction which enableto  provide local accurate representations and an a posteriori limitation to prevent from...

##### Limiting embeddings in smoothness Morrey spaces, and applications
2014-10-03
Speaker: Dorothee D. Haroske (Univ. Jena, Germany)
...

##### Computational methods in the fractional calculus of variations
2014-10-01
Speaker: Delfim F. M. Torres (Univ. Aveiro)
The fractional calculus of variations and fractional optimal control are generalizations of the corresponding classical theories, allowing problem modeling and formulations with arbitrary order derivatives and integrals. Because of the lack of analytic methods to solve such fractional...

##### Combinatorial Brill-Noether theory
2014-10-01
Speaker: Jorge Sentieiro Neves (CMUC / Univ. Coimbra)
The theory of linear systems on graphs is a recent branch of combinatorics owing its fast development to a link with algebraic and tropical geometry. We will review the general theory leading up to the Brill-Noether theorem, whose purely combinatorial proof is an open problem....

##### Fundamental group functors and higher Hopf formulae
2014-09-30
Speaker: Mathieu Duckerts-Antoine (CMUC)
In 1988, R. Brown and G. J. Ellis gave Hopf formulae for the integral homology of a group using topological methods. G. Janelidze first recognized that these descriptions are deeply connected with the categorical Galois-theoretic notion of covering morphism. Using this perspective, T....

##### Lax algebras as spaces
2014-09-30
Speaker: Maria Manuel Clementino (CMUC, Univ. Coimbra)
Following [1], in this talk we look at lax algebras as spaces, exploring their topological properties like compactness, Hausdorff separation, regularity, normality and extremal disconnectedness. [1] M.M. Clementino, E. Colebunders, W. Tholen, Lax algebras as spaces, in: Monoidal...

##### On approximation by periodic splines: theory and application
2014-09-24
Speaker: Rolf D. Grigorieff (Technische Univ. Berlin, Germany)
The talk is concerned with the existence of multiple knot periodic splines satisfying general Hermite interpolation conditions and their approximation power in Sobolev spaces. The key for such results are necessary and sufficient conditions for the existence of interpolating cardinal splines...

##### A new class of integer valued processes with conditional heteroscedasticity
2014-09-19
Speaker: Filipa Silva (CMUC)
The aim of this talk is to introduce an integer-valued model with conditional distribution belonging to the class of compound Poisson probability laws. This proposal includes, in particular, the Poisson INGARCH model, and the negative binomial and generalized Poisson models. We show the...

##### Electrostatic interpretation of roots of polynomials satisfying certain 2nd order differential equations
2014-09-19
Speaker: Edmundo Huertas Cejudo (CMUC)
In the last years some attention has been paid to the so called canonical spectral transformations of measures. This talk is focused on the behaviour of zeros of monic orthogonal polynomial sequences (MOPS in short) associated with the so called Geronimus canonical transformation, which...

##### The pointfree representation of a truncated archimedean l-group
2014-09-11
Speaker: Richard N. Ball (Univ. Denver, USA)
In this talk we develop the analog for truncated archimedean lattice-ordered groups, hereafter referred to as truncs, of Madden's pointfree representation for W, the category of archimedean l- groups with designated weak order unit. In the first part of the talk we will motivate the notion...

##### Pointfree pointwise suprema in archimedean l-groups
2014-09-10
Speaker: Richard N. Ball (Univ. Denver, USA)
We generalize the concept of the pointwise supremum of real-valued functions to the pointfree setting. The concept itself admits a direct and intuitive formulation which makes no mention of points. But our aim here is to investigate pointwise suprema of subsets of RL, the family of...

##### Mathematics in Industry: Some successful collaborations
2014-09-10
Speaker: Manuel B. Cruz (LEMA/ISEP)
The interaction Mathematics-Industry has suffered a great development in the latest years. The genesis of EU-MATHS-IN, the European Network for Mathematics in Industry, as well as the spread of several national networks across Europe, illustrates the evolution and potential of that area of...

##### An overview of some Spanish infrastructure focused on promoting the transfer of mathematics to industry
2014-09-10
Speaker:
Peregrina Quintela (Univ. Santiago de Compostela)
In the talk two infrastructures aimed at boosting transfer to industry will be presented: The Spanish Network for Mathematical and Industry (math-in) and the Technological Institute of Industrial Mathematics (ITMATI). Some details of how they were formed, the type of legal entity chosen, the...

##### Optimal basis algorithm and its application to matrix scaling
2014-07-25
Speaker: Oleg Burdakov (Linköping Univ., Sweden)
We present the optimal basis (OB) problem and the OB algorithm that we proposed in BIT (1997) {\bf 37}, 591-599. The OB problem is formulated as follows. Given $m+1$ points $\{x_i\}^{m}_{0}$ in $R^n$ which generate an $m$-dimensional linear manifold, construct for this manifold a maximally...

##### Dimension counts for singular rational curves
2014-07-23
Speaker: Ethan Cotterill (Univ. Federal Fluminense, Niterói, Brazil)
Rational curves are essential tools for classifying algebraic varieties. Establishing dimension bounds for families of embedded rational curves that admit singularities of a particular type arises naturally as part of this classification. Singularities, in turn, are classified by their value...

##### Composition factors of a tensor product of several symmetric powers
2014-07-16
Speaker: Stephen Donkin (Univ. of York, UK)
We consider the problem of determining which irreducible polynomial modules occur as a composition factor of an m-fold tensor product of symmetric powers of the natural module for the general linear group. The case m=1 was analysed by Krop and Sullivan and they obtained (independently) a...

##### Mehler-Heine asymptotics of polynomials
2014-07-16
Speaker: Juan J. Moreno Balcázar (Univ. Almeria, Spain)
In this talk, we will give an overview about Mehler--Heine asymptotics of polynomials. This type of formulae is well known for very classical Jacobi, Laguerre and Hermite polynomials. We pay attention to recent results obtained for other families of polynomials such as generalized...

##### The spectral theorem on the para-orthogonality theory
2014-07-16
Speaker: Kenier Castillo (UNESP, Brazil)
Our goal is to provide the para-orthogonality theory with a new powerful tool for computing: recurrence relation. Analogous results to the classicals Favard and Geronimus-Wendroff theorems are deduced....

##### Compact embeddings of weighted Sobolev spaces
2014-07-11
Speaker: Therese Mieth (Friedrich-Schiller-Univ. Jena, Germany)
The abstract is in the attached pdf file ...

##### Kan-injectivity in Top0 and Kan-projectivity in Frm
2014-07-10
Speaker: Margarida Carvalho (ISCAC)
In the context of categories enriched in the category of partial order sets, we will work with KZ-reflectivity and Kan-injectivity, notions which, as we shall see, are closely related.We will show that there is an infinite chain of small subcategories of the category Top0, whose...

##### Lax orthogonal factorisation systems
2014-07-10
Speaker: Maria Manuel Clementino (CMUC)
In [4] Grandis and Tholen introduced natural weak factorisation systems (also called algebraic weak factorisation systems, see [3]) as pairs (L,R), where L is a comonad and R is a monad subject to suitable conditions, and showed that orthogonal factorisation systems are the natural weak...

##### Generalizations of generating functions for orthogonal polynomials in the Askey and q-Askey schemes
2014-07-09
Speaker: Howard S. Cohl (National Institute of Standards and Technology, USA)
In this talk, we present generalized generating functions for generalized hypergeometric and basic hypergeometric orthogonal polynomials. These generalized expansions are obtained by re-expressing the polynomials in the generating functions using multi-parameter connection relations. The...

##### Non-Fickian models for biodegradable drug eluting stents
2014-07-09
Speaker: Jahed Naghipoor (CMUC)
In recent years, mathematical modeling of cardiovascular drug delivery systems has become an effective tool to gain deeper insights in the cardiovascular diseases like atherosclerosis. In the case of coronary biodegradable stent which is a tiny expandable metallic mesh tube covered by...

##### Effective cones of higher codimension cycles on moduli spaces of curves
2014-07-09
Speaker: Izzet Coskun (Univ. of Illinois at Chicago, USA)
I will report on joint work with Dawei Chen where we study effective cones of higher codimension cycles on moduli spaces of curves.We show certain geometrically defined cycles span extremal rays in the effective cone. In particular, we prove that codimension two boundary strata are extremal....

##### On Butler's conjecture
2014-07-02
Speaker: Leticia Brambila-Paz (CIMAT, Mexico)
D.C. Butler conjectured that the kernel of the evaluation map of a general generatedcoherent system over a general curve is stable. In this talk I will explain theproof of the conjecture for linear series. This is a joint work with Usha Bhosleand Peter Newstead....

##### Hypersymplectic and hyperkähler structures with torsion
2014-06-25
Speaker: Paulo Antunes (CMUC)
We define hypersymplectic structures with torsion (HST) on Lie algebroids and establish a 1-1 correspondence between hyperkähler structures with torsion (HKT) and HST structures. We also obtain a contravariant definition of both HKT and HST structures on Lie algebroids. Additionally, we...

##### Towards a calculus of fractions concerning Kan-injectivity
2014-06-24
Speaker: Lurdes Sousa (CMUC and IP Viseu)
In an order-enriched category $\cal X$, for a given subcategory $\cal A$, we study the class ${\cal A}^{KInj}$ of all morphisms with respect to which $\cal A$ is Kan-injective. We show that, for $\cal A$ an arbitrary subcategory of $\cal X$, ${\cal A}^{KInj}$ is, in a certain sense, closed...

##### The Karoubi envelope of sofic, Markov-Dyck and Property (A) shifts
2014-06-24
Speaker: Alfredo Costa (CMUC)
In this talk, we discuss some recent results, obtained jointly with Benjamin Steinberg, about the Karoubi envelope of the syntactic semigroup of a shift. We see that, in a natural way, the Karoubi envelope is the best possible syntactic invariant of flow equivalence of sofic shifts. ...

##### The average covering number of a graph
2014-06-23
Speaker: Derya Dogan (Celal Bayar Univ., Turkey)
There are occasions when an average value of a graph parameter gives more useful information than the basic global value. In this talk, we introduce the concept of the average covering number of a graph (the covering number of a graph is the minimum number of vertices in a set with the...

##### Boundary integral methods using implicitly defined interfaces and their applications
2014-06-20
Speaker: Richard Tsai (Univ. of Texas at Austin, USA)
I will describe a new framework for building numerical methods for boundary integral equations using implicit surface representation. Such setting is natural for many problems that involve bulk-diffusion driven nonlinear interface dynamics in irregular and unbounded domains. Typically the...

##### Polar maps, foliations, characteristic classes
2014-06-18
Speaker: Nivaldo Medeiros (Univ. Fluminense, Brazil)
To each hypersurface X in the projective n-space, we associate a rational map Pn--->Pn, called its polar map, given simply by the partial derivatives of the polynomial that deﬁnes X. This is a classical theme in projective geometry; the central problem is the classiﬁcation...

##### Boundary points of the ELSV compactification
2014-06-11
Speaker: Bashar Dudin (CMUC)
The celebrated ELSV formula relates the number of covers of the projective line having a given profile over one point and fixed branch points to intersection numbers on the the moduli space of stable marked curves. The former number is essentially of combinatorial nature and boils down to...

##### Moderate deviations for dependent variables
2014-06-06
Speaker: Paulo Eduardo Oliveira (CMUC)
Large and moderate deviations are an important topic in many theoretical or applied statistical areas. We start by a brief overview of large deviations, mentioning the results for dependent variables. A special interest is put for exact convergence rates. After a first quick look at exact...

##### Explicit Leap-frog DG method for time domain electromagnetic wave propagation
2014-06-04
Speaker: Maryam Khaksar Ghalati (CMUC, Univ. Coimbra)
The discontinuous Galerkin time domain methods are now popular and efficient way for the solution of wave propagation problems. The motivation of modeling scattered electromagnetic wave propagation through the human eye’s structure brings us to solving aMaxwell’s equations with...

##### Nonlinear propagation of waves of short wavelength in dispersive systems
2014-05-28
Speaker: Sílvio Gama (Univ. Porto)
We discuss the nonlinear propagation of waves of short wavelength in dispersive systems and we present the simplest nonlinear short-wave dynamics: $u_{tx} = u - 3 u^2$. We present an algorithm to integrate numerically this equation for periodic and non-periodic boundary conditions. We also...

##### Medical image processing using the image derivatives
2014-05-23
Speaker: Alberto Gambaruto (Barcelona Supercomputer Center, Spain)
Medical image processing remains an active field of research principally due to the difficulty of defining the problem. The most successful approaches are related to solving PDEs that model anisotropic diffusion, where the anisotropy is given spatially by the image gradient or Laplacian,...

##### Nonlocal models for image processing: properties and applications
2014-05-23
Speaker: Eduardo Cuesta (Univ. Valladolid, Spain)
One of the alternatives for the mathematical formulation of image processing problems is based on local, nonlinear PDEs models. In the first part of the talk, a brief overview of them, with special regards to morphological and structural properties, will be done. In the second part, some...

##### Gangster operators and invincible positive semi-definite matrices
2014-05-21
Speaker: Charles R. Johnson (The College of William & Mary, USA)
In the relatively new subject of semidefinite programming, positive definiteness plays the role of scalar positivity and inequalities in the PSD partial order replace standard inequalities, relative to linear programming. The subject hashad great success in solving or approximately solving...

##### On the numerical approximation of algebraic equations with symmetries
2014-05-21
Speaker: Angel Durán (Univ. Valladolid, Spain)
The resolution of systems of algebraic equations with symmetry groups appears in the mathematical treatment of many models, [1, 2]. These groups consist of transformations that map solutions of the algebraic system into other solutions. Some consequences of the existence of such symmetry...

##### Trigroups and M-theory
2014-05-20
Speaker: John Huerta (CMAGDS, IST, Lisboa)
A trigroup is a tricategory with one object and all 1-, 2- and 3-morphisms invertible. M-theory is a mysterious branch of physics believed to unify the five 10D string theories and 11D supergravity. Without assuming any knowledge of physics, we will describe how the mathematics of M-theory...

##### Pattern formation on evolving biological surfaces: the surface fi nite element method applied to reaction-diff usion systems
2014-05-16
Speaker: Raquel Barreira (IP Setúbal)
The abstract is in the attached pdf file...

##### Semisimple Hopf algebra actions
2014-05-07
Speaker: Christian Lomp (Univ. Porto)
We review Hopf algebra actions on rings with particular emphasis on a question raised by Miriam Cohen in 1985 whether the smash product A\# H of a semisimple Hopf algebra H acting on a semiprime algebra A is itself a semiprime ring. This question is open until now. In my talk I give a...

##### Growth and periodicity in representation theory
2014-05-07
Speaker: Karin Erdmann (Univ. Oxford, UK)
We consider finite-dimensional modules of finite-dimensional algebras. Any such module has a (unique) minimal projective resolution, that is, a resolution where terms are direct summands of free modules, as small as possible. One would like to know its rate of growth, known as the...

##### The geometry and topology of random simplicial complexes.
2014-04-23
Speaker: Armindo Pereira da Costa (Univ. Warwick, UK)
In this talk we will explore the topological features of random simplicial complexes. We will introduce two models that extend the Erdős–Rényi model for generating random graphs. Unlike in the one-dimensional case (random graphs), we may...

##### A parabolic Harnack inequality for a nonlocal in time diffusion equation
2014-04-09
Speaker: Juhana Siljander (Univ. Helsinki, Finland)
Nonlocal PDEs have gathered a lot of interest during the last years. In particular, the fractional Laplacian and its generalizations have been studied extensively recently. In this talk we will discuss a different kind of nonlocal equation: namely a parabolic diffusion model where the ...

##### Weighted Sobolev orthogonal polynomials on the unit ball
2014-04-09
Speaker: Miguel Piñar (Univ. Granada, Spain)
For the classical weight function on the unit ball, a Sobolev inner product involving the gradient operator is considered. For this inner product a family of mutually orthogonal polynomials on the unit ball is constructed in terms of spherical harmonics and a sequence of Sobolev orthogonal...

##### On Chow stability for algebraic curves
2014-04-09
Speaker: Hugo Torres Lopez (CIMAT, Mexico)
In the last decades there have been introduced different concepts of stability for proyective varieties. In this talk we recall the Chow stability introduced by Mumford for projective varieties, and we prove a natural and intrinsic criterion of the Chow stability for irreducible smooth...

##### Normality and its weaker forms
2014-04-08
Speaker: Mack Matlabyana (Univ. of Limpopo, South Africa)
In this talk we characterize normality and the weaker variants of normality by some quotient maps, namely, uplifting quotient maps, C1-quotient maps, R*- and G*-quotient maps....

##### Normal semicontinuous functions in pointfree topology and weak cb-frames
2014-04-08
Speaker: Imanol Mozo Carollo (Univ. of the Basque Country, Bilbao, Spain)
In a recent paper [2], we have constructed the Dedekind completion of the lattice C(L) of continuous real functions on a frame L, in terms of normal semicontinuous functions. Of course, this construction evokes the classical description of the completion of C*(X) (bounded continuous real...

##### Generalized Bargmann transforms attached to Landau levels
2014-04-04
Speaker: Zouhair Mouayn (Univ. Coimbra)
We construct a family of generalized Bargmann transforms mapping isometrically the states Hilbert spaces of specific Hamiltonian operators onto  L2-eigenspaces associated with Landau levels of a uniform magnetic field on the Euclidean plane, the Poincaré disk and the Riemann...

##### Educational interfaces between Mathematics and Industry. Report on an ICMI-ICIAM Study.
2014-04-04
Speaker: Rudolf Strässer (J.L. Univ. Giessen, Germany & A.C. Univ. Brisbane, Australia)
The presentation will offer some results of the joint ICMI-ICIAM-study on "Educational Interfaces between Mathematics and Industry (EIMI)", which finished in 2013. Elaborating on Mathematics in these different institutions, it will briefly present the role of...

##### Hermitian matrices and Hodge numbers of irregular algebraic surfaces
2014-04-02
Speaker: Margarida Mendes Lopes (IST/UL)
In this talk it will be explained how properties of spaces of hermitian matrices can be used to obtain lower bounds for the h^1,1 Hodge number of irregular algebraic surfaces and in particular to show the non existence of surfaces with certain invariants. After a brief explanation of the...

##### Universality laws for time-frequency ensembles
2014-03-28
Speaker: Luís Daniel Abreu (ARI-Austrian Acad. of Sciences)
There is a transdisciplinar idea known as "Universality" which aims to understand how the macroscopic laws of nature can be obtained from those ruling the microscopic world. The following phenomenon seems to be pervasive: often, a system of interacting objects (for instance,...

##### Taylor property revisited
2014-03-28
Speaker: Joana Leite (CMUC and Instituto Politécnico de Coimbra, ISCAC)
Empirical properties systematically observed in time series of a certain field play an important part in scrutinizing models, as models proposed for them should be able to reproduce these, so called, stylized facts. The Taylor effect is a stylized fact regarding the autocorrelation...

##### On special class of para-orthogonal polynomials
2014-03-21
Speaker: Kenier Castillo (Univ. Estadual Paulista, Sao Paulo, Brazil)
We study the zeros in connection with perturbed recurrence coefficients of polynomials satisfying a certain three-term recurrence relation.   As a particular case, we consider the Askey para-orthogonal polynomials on the unit circle, ${_2}F_1(-n, a+b i; 2 a; 1-z)$, $a,b \in \re$,...

##### Virial Theorem in Lagrangian formalism
2014-03-19
Speaker: Patrícia Santos (CMUC/ISEC)
In this talk the geometric approach to the virial theorem in Lagrangian formalism is presented in quasi-velocities, and a generalization of the virial theorem on Lie algebroids is given. The virial theorem was introduced by Clausius in statistical mechanics in 1870 and since then it became...

##### Monoids and pointed S-protomodular categories
2014-03-18
Speaker: Andrea Montoli (CMUC, Univ. Coimbra)
We investigate the notion of pointed S-protomodular category, with respect to a suitable class S of split epimorphisms, and we show that these categories satisfy, relatively to the class S, many partial aspects of the properties of Mal'tsev and protomodular categories, like the split short...

##### Geodesic paths and weakly Mal'tsev categories
2014-03-18
Speaker: Nelson Martins Ferreira (CDRSP, ESTG, IP Leiria)
We introduce an algebraic structure with the purpose of modelling an arbitrary space with a suitable notion of geodesic path for every two points in it. We prove that this structure satisfies a weak Mal'tsev property, and show that any smooth surface in which every two points are linked by a...

##### Wasserstein metric and seismic exploration
2014-03-12
Speaker: Bjorn Engquist (Univ. of Texas at Austin, USA)
In seismic exploration a wave field is generated at the surface and reflections from the earths interior are recorded. The purpose is to find properties such as wave velocity and location of reflecting sub layers. This can be in an inverse problem where the ...

##### Non local phase transitions
2014-03-07
Speaker: Yannick Sire (Univ. d'Aix-Marseille, France)
I will describe a few recent results dealing with the Allen-Cahn equations with a fractional laplacian. The results are in connection with a fractional version of a conjecture by De Giorgi. I will also explain several open problems and what is the state of the art....

##### Orthogonal polynomials associated with Laguerre weight matrix
2014-03-05
Speaker: Nikta Shayanfar (K. N. Toosi Univ. of Technology, Tehran, Iran)
We study a sequence of matrix polynomials (Pn)n of size nxn, which are orthogonal with respect to the weight matrix involving the classical Laguerre scalar weight.  This family of orthogonal matrix polynomials satisfy a second order differential equation with coefficients ...

##### Sums of squares on the hypercube
2014-03-05
Speaker: João Gouveia (CMUC/Univ. Coimbra)
Let X be a finite set of points in R^n. A polynomial p nonnegative on X can be written as a sum of squares of rational functions modulo the vanishing ideal I(X). We are interested in the existence of rational function representations of small degree. We will show how to derive a general...

##### Surfaces with p_g=0, K^2=3 and 5-torsion
2014-02-26
Speaker: Carlos Rito (Univ. Porto)
There is (almost) no information available on the literature about complex algebraic surfaces of general type with geometric genus pg=0, self-intersection of the canonical divisor K2=3 and with 5-torsion.If S is a quintic surface in P3 having 15 3-divisible ordinary cusps as only...

##### Bullwhips, conservation laws and 1-Laplacian
2014-02-07
Speaker: Dmitry Vorotnikov (CMUC, Univ. Coimbra)
We study the equation of motion for inextensible strings with the "whip" boundary  conditions. We prove existence of generalized Young measure solutions after  transforming the equation into a system of conservation laws and approximating it with a regularized system...

##### GLODS: Global and Local Optimization using Direct Search
2014-02-05
Speaker:

Ana Luísa Custodio (Univ. Nova de Lisboa, Portugal)

Locating and identifying points as global minimizers is, in general, a hard and time-consuming task. Difficulties increase when the derivatives of the functions defining the problem are not available for use. In this talk, we propose a new class of methods suited for global derivative-free...

##### Combinatorial Game Theory: a survey
2014-02-05
Speaker: Carlos Pereira dos Santos (ISEC)
In the first years of the 20th century the analysis of the game of nim (by the mathematician Charles L. Bouton) triggered the outburst of a completely new mathematical subject: Combinatorial Game Theory. The aim of this seminar is to give a survey of the development of this mathematical...

##### On the Gromov width of polygon spaces
2014-02-05
Speaker: Alessia Mandini (Univ. of Pavia, Italy)
After Gromov' foundational work in 1985, problems of symplectic embeddings lie in the heart of symplectic geometry. The Gromov width of a symplectic manifold (M,\omega) is a symplectic invariant that measures, roughly speaking, the size of the biggest ball we can symplectically embed in...

##### A Cohen type inequality for Laguerre-Sobolev expansions
2014-01-31
Speaker: Maria Francisca Perez Valero (Univ. Carlos III, Madrid, Spain)
In the framework of approximation theory, a Cohen type inequality is a lower bound for the norm of the partial sums of the Fourier expansions in terms of a certain orthogonal system. This kind of inequalities have been investigated by many authors in various contexts and forms, including...

##### 2A-replication and the Baby Monster
2014-01-22
Speaker: Rodrigo Farinha Matias (CMUC, Univ. Coimbra)
In the first half of this seminar we will make an introduction to "Moonshine". Namely, we will talk about modular forms, Hecke operators, the Monster Group, Kac-Moody-Lie algebras, vertex algebras, replicability of power series and how these structures are all interrelated to each...

##### Attractors of trajectory spaces in fluid mechanics
2014-01-10
Speaker: Stanislav Kondratyev (CMUC, Univ. Coimbra)
It often happens in fluid mechanics that initial and boundary value problems are not known to be uniquely solvable.  In this case the dynamics can be appropriately treated in terms of trajectory spaces.  The talk will review a few concepts of attractors applicable to trajectory...

##### Derivatives for equational theories and a special case of Taylor's conjecture
2014-01-09
Speaker: Luís Sequeira (CAUL, Univ. Lisboa)
The theory of Maltsev conditions has provided many useful characterizations of properties of varieties, like permutability or modularity of congruence lattices, by the satisfaction of certain identities. The notion of "derivative" for a  an equational theory (or, equivalently,...

##### The set of equational classes of finitary functions on a finite set as a profinite semigroup
2014-01-09
Speaker: Jorge Almeida (CMUP, Univ. Porto)
For a fixed finite set A, we consider sets of finitary functions (or operations) on A, henceforth called classes. We are interested in such classes that can be defined by certain functional equations. It turns out that they constitute a semigroup under the natural notion of class...

##### Numerical solution of Sturm--Liouville problems via Fer streamers
2014-01-08
Speaker: Alberto Gil C. P. Ramos (Univ. Cambridge, UK)
We address the numerical challenge of solving Sturm-Liouville problems in Liouville's normal form, with regular boundary conditions and a continuous and piecewise analytic potential. The novelty of our approach, which is based on a non-standard truncation of Fer expansions, which we call...

##### On closure properties of some risk aversion measures
2013-12-17
Speaker: Nuria Torrado-Robles (CMUC, Univ. Coimbra)
Increasing risk aversion (IRRA) is a common assumption in economics, but this property often is difficult to verify. In this talk, we provide alternative characterizations of IRRA utility functions in terms of increasing absolute risk aversion (IARA) utility functions. We also present some...

##### The symmetrization problem in the theory of multiple orthogonal polynomials
2013-12-06
Speaker: Edmundo Huertas Cejudo (CMUC, Univ. Coimbra)
For a symmetric sequence of type II multiple ortogonal polynomials satisfying a high-term recurrence relation, we provide the relationship between the Weyl function associated to the corresponding block Jacobi matrix and the Stieltjes matrix function. Next, from an arbitrary (and not...

##### Rainbow connection in graphs
2013-12-04
Speaker: Henry Liu (Univ. Nova de Lisboa)
For a connected graph G, the rainbow connection number rc(G) is the minimum number of colours required to colour the edges of G so that, any two vertices are connected by a "rainbow" path (i.e., using distinct colours). The function rc(G) was introduced by Chartrand, Johns, McKeon...

##### Supercharacters, non-commuting symmetric functions and set partition combinatorics
2013-11-27
Speaker: Carlos André (Univ. Lisboa)
The representation theory of the symmetric group is a fundamental model in combinatorial representation theory because of its connections to partition and tableaux combinatorics. It has become clear in recent years that the super-representation theory of the finite unitriangular group has a...

##### Financial risk measures
2013-11-26
Speaker: Miguel Mendes (FEUP/CMUP, Univ. Porto)
We review the concept of risk measure and its use as a capital requirement in the financial industry or as a premium in the insurance context. We then consider the Choquet integral as an important representation of risk measures and specialise to distortion risk measures. Our main innovation...

##### Dynamics and interpretation of some integrable systems via orthogonal polynomials
2013-11-22
Speaker: Amílcar Branquinho (CMUC, Univ. Coimbra)
We establish the correspondence between a non symmetric difference operator with complex coefficients and the evolution of an operator deﬁned by a Lax pair. We study the solution of the discrete dynamical system, giving explicit expressions for the resolvent function associated with...

##### Mathematical modelling of Angiogenesis -flow, elasticity and experiments
2013-11-20
Speaker: Rui Travasso (Center for Computational Physics, Univ. Coimbra)
Understanding angiogenesis in a pathological setting is a challenging problem with important consequences for diagnosis and treatment of severe diseases such as cancer. We present a multi-scale phase- field model that combines the benefi ts of continuum physics description and the capability...

##### Codes over a weighted torus
2013-11-13
Speaker: Jorge Sentieiro Neves (CMUC, Univ. Coimbra)
We will describe a new family of linear codes, extending the notion of projective generalized Reed-Muller codes to a setting where the grading of the polynomial ring is non-standard. We will show how the invariants of the numerical semigroup generated by the weights of the variables come...

##### Essential spectrum for graphs of radial functions
2013-11-08
Speaker: Fábio Montenegro (UFC, Brazil)
We prove that if M is a complete hypersurface in R^{n+1} which is the graph of a real radial function, then the spectrum of the Laplace operator on M is the interval [0, \infty)....

##### On the weak-approximate fixed point property
2013-11-08
Speaker: Cleon Barroso (UFC, Brazil)
In this talk we will present a research line known as weak-approximate fixed point property. Some related problems and contributions will be addressed. We will also present some interesting applications related to the fixed point theory, and also to the theory of ordinary differential...

##### On the contributions of lattice theory to the study of persistent homology.
2013-11-06
Speaker: João Pita Costa (Josef Stefan Institute, Liubliana, Slovenia)
In the past 20 years Topological Data Analysis has been a vibrant area of research a lot due to the developments in applied and computational algebraic topology. Essentially it applies the qualitative methods of topology to problems of machine learning, data mining or computer vision. Under...

##### Geometric Quantum Mechanics and applications
2013-11-06
Speaker: Jesús Clemente-Gallardo (Univ. Zaragoza, Spain)
We can notice that the approaches to Classical and Quantum Mechanics are quite different in many aspects, the most striking one being the linear structure which is present in the Hilbert space H and which is considered usually as one of the most relevant aspects of the formalism. There are...

##### Optimal control applications in blood flow simulations
2013-10-30
Speaker: Jorge Tiago (IST, Lisboa)
Blood flow simulations can be improved by integrating known data into the numerical simulations. Data assimilation techniques based on a variational approach can have an important role on this. We will introduce a nonlinear optimal control problem to reconstruct a blood flow profile from...

##### Some recent developments of a non-dissipative DGTD method for time-domain electromagnetics
2013-10-29
Speaker: Stéfane Lanteri (INRIA Sophia Antipolis-Méditerranée)
Nowadays, a variety  of modeling  strategies exist for the computer simulation of electromagnetic wave propagation in the time domain. Despite a lot of advances on numerical methods able to deal accurately and in a flexible way with complex geometries through the use of...

2013-10-25

##### Uma nova técnica de rotulação para o problema do trajecto mais curto multi-objectivo
2008-02-28
Speaker: José Luís Esteves dos Santos
O problema do trajecto mais curto multi-objectivo (PTMCM) é definido numa rede em que vários critérios são atribuídos a cada arco. Em geral, existe conflito entre os vários objectivos pelo que a resolução do PTMCM consiste na determinação dos trajectos não-dominados (ND), isto é,...

##### Nonlinear eigenvalues for anisotropic quasilinear degenerate elliptic equations
2008-02-15
Speaker: Agnese Di Castro (University of Rome "La Sapienza")
I will speak about recent results obtained in collaboration with Eugenio Montefusco of the University of Rome "La Sapienza". We study the questions of existence, nonexistence and multiplicity of positive solutions for a class of anisotropic quasilinear elliptic equations with Dirichlet...

##### A universal construction in Goursat categories
2008-02-12
Speaker: Diana Rodelo (CMUC/U. Algarve)
We prove that the category of internal groupoids Grd(E) is a reflective subcategory of the category Rg(E) of internal reflexive graphs in a regular Goursat category E with coequalisers: this implies that the category Grd(E) is itself regular Goursat. Area(s): ...

##### Leis max-semiestáveis como limite do máximo em modelos MA e max-AR de variáveis inteiras
2008-02-07
Speaker: Maria da Graça Temido (CMUC & FCTUC)
Analisamos a convergência em distribuição do máximo, linearmente normalizado, em modelos estacionários de médias móveis e max-autorregressivos de variáveis inteiras. Consideramos o caso particular em que a função de distribuição marginal não pertence a nenhum domínio de atracção max-estável,...

##### Wavelets: From the real line to the unit sphere
2008-02-01
Speaker: Milton Ferreira (Instituto Politécnico de Leiria)
Wavelet theory is applicable to several subjects and fields of science. All wavelet transforms may be considered forms of time-frequency representation for continuous-time (analog) signals and so are related to harmonic analysis. A wavelet is a kind of mathematical function used to divide...