Path:  Home   >  Historic (Seminars)

Seminars - Historic

<Theme details>
 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 (Universidade...

 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 (unions...

 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 of...

 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

 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) domain R...

 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. And, as...

 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 in order...

 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 eigenvalue...

 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 out that...

 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 likely...

 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 or...

 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 codomain B...

 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 explore the...

 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 rings,...

 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 results...

 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 thesis...

 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 Green 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, but are...

 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 they are...

 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. Since 90's...

 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 pde's but...

 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 of the...

 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 special...

 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 sufficient level...

 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 [1],[2]) like...

 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). Non-linear...

 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 important, as...

 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 concerning the...

 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 leads in...

 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 is...

 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 thus...

 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 resampled...

 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 duality)...

 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 is...

 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 oscillations...

 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 algebraic...

 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 view, from...

 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 change of...

 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 g-1,...

 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 special...

 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 in...

 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 an...

 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 subcategory of...

 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 called...

 TBA 2018-11-14 Speaker: Hugo Peña Gomez (UC|UP PhD Programme student) TBA...

 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 intersection of...

 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 provided with...

 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 we find...

 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 composite...

 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: limit...

 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 describes...

 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 left...

 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 that...

 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 * (resp....

 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 by...

 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 can be...

 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 hyperbolic...

 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 cell...

 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 varieties)...

 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 natural...

 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 Hausdorff...

 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 step is...

 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 generalised...

 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 Chiara...

 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 cone, the...

 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 of...

 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 combinatorics...

 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 singular...

 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 compact...

 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 of degree...

 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 with...

 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 construct...

 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 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 other...

 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 of A is...

 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 the...

 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 fluid...

 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 mild...

 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 talk I...

 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 continuous...

 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 using...

 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 example where...

 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 a...

 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 strong...

 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 were...

 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 Speaker: José Luis Cardoso (CM-UTAD) 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 of the...

 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 with the...

 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 coefficient...

 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 what...

 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 the...

 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 Galicia...

 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 the...

 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 of random...

 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 our...

 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 these...

 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 first...

 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 examples. The...

 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 boundary....

 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 triangle...

 Time-analyticity of fluid particle trajectories in ideal fluid flow 2017-11-08 Speaker: Vladislav Zheligovsky (Russian Academy of Sciences) 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 of the...

 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 concept to the...

 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 MFGs...

 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 (positive...

 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 using...

 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 testing...

 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. We...

 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 two...

 Oscillatory and nonoscillatory behavior of a differential delay system of order n 2017-10-11 Speaker: Sandra Pinelas (Academia Militar) 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 description...

 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 sublocales...

 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 semigroups. Many...

 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 present...

 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 inferred...

 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. Volkov,...

 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 hypermaps...

 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 Speaker: Azizeh Nozad (Univ. Lisboa) 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 theory...

 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 (x°y=xy+yx)....

 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 an...

 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 theory,...

 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 stability of the...

 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 coalgebra has a...

 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 matrices, the...

 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 quantum...

 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 it to...

 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 of...

 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 Lawvere,...

 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) can be...

 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 immediately...

 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 expectation is...

 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 structure...

 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 almost...

 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 numerical...

 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 possible for...

 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 S-protomodular...

 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 interesting...

 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 their...

 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 of...

 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 talk I will...

 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 global...

 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 and...

 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 unified...

 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 some...

 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 classical...

 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 version for...

 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 are...

 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 the...

 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 geometric...

 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 applications...

 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 type....

 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 algorithms...

 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) and the...

 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 algebra...

 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 monomials....

 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 population ui...

 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 results of...

 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 categorical...

 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 Speaker: Mohamed Boucetta (Univ. Cadi-Ayyad, Marrakech, Morocco) 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 case, we...

 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 solutions...

 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 the...

 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 able to...

 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 of...

 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 smoothness....

 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 p-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 facilities.In...

 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 replace...

 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 many...

 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 concrete for...

 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 context...

 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. Despite...

 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 Quantum...

 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 an...

 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 its...

 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 commonly...

 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 detailed...

 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, the...

 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 the...

 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 is joint...

 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 those...

 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 semigroup...

 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 that it...

 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 dPIV....

 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 problems...

 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 suitably...

 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 but for...

 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 obtained...

 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 under...

 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 talk...

 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 explicit...

 Nijenhuis deformation of Gerstenhaber algebra and Poisson Quasi-Nijenhuis algebroids 2016-04-27 Speaker: Mohammad Jawad Azimi (CMUC/Univ. Coimbra) 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 algebroids,...

 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 promising...

 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 presents the...

 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 there is a...

 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 notion...

 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 context...

 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 techniques are...

 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 different...

 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 mathematical...

 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 manifold is...

 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 ideas...

 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 fibration of...

 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 of finite...

 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 Thomas...

 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 homology and...

 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 structure....

 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 one...

 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 based on...

 Toric constructions of monotone Lagrangian submanifolds in CP^2 and CP^1 x CP^1 2016-01-27 Speaker: Agnès Gadbled (Univ. Porto) 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 standard...

 Computational modeling of hematopoietic stem/progenitor cells expansion and differentiation 2016-01-20 Speaker: Javad Hatami (Univ. Minho) 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 quantitatively...

 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 Problem...

 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 divisibility....

 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 differences...

 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 multiplicity...

 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 different ways...

 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 medicine....

 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 $\alpha.$...

 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 and the...

 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

 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 with...

 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 for...

 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 abelian...

 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 are...

 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 fibred Lie...

 On pseudovarieties of forest algebras 2015-10-27 Speaker: Saeid Alirezazadeh 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 plane...

 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 results....

 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 map in a...

 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 it to...

 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 with...

 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 dually...

 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 first...

 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 equals...

 Birationality of moduli spaces of twisted U(p,q)-Higgs bundles 2015-09-29 Speaker: Azizeh Nozad (Univ. Porto) 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 twisted...

 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 weak)...

 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 are...

 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 between...

 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 initial...

 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 functions on...

 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 combined...

 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 image...

 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 category,...

 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 model....

 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 tangent bundle TM....

 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 results...

 Arbitrary triple systems admitting a multiplicative basis 2015-06-18 Speaker: José María Sánchez Delgado (Univ. Cadiz, Spain) 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 same...

 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 to World...

 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 answer for...

 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 Ping Xu....

 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 involving...

 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 question that...

 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 description...

 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 respect...

 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, Aldo...

 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 increasing...

 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 space. The...

 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 energy...

 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 which...

 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 tem ...

 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 of...

 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 signals...

 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 discrete...

 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 address the...

 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 a...

 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 are...

 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 pointfree...

 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 with...

 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 representations of...

 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 difficulties show...

 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 approximants...

 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 different...

 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 the...

 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 basic...

 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...

 On Randic spread 2015-02-04 Speaker: Enide Andrade (Univ. Aveiro) 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 index...

 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 simple...

 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 functions,...

 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 equipped with...

 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 in...

 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 of the...

 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 symmetries, etc....

 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 to obtain...

 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 actions, or...

 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 established a...

 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 conditions...

 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 Speaker: André G. Oliveira (UTAD) 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 X and G....

 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 the...

 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 naturally...

 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 characterise in...

 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. In the...

 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 problems,...

 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. Everaert, M....

 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 Topology, A...

 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 which...

 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 relevance of...

 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 consist of a...

 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 of...

 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 continuous real...

 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 linearly...

 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 theorem...

 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 hypergeometric...

 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 Kan-injective hulls...

 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 resulting...

 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 biodegradable...

 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. We also...

 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 prove...

 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 under...

 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. Outside the...

 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 property that...

 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 evolving...

 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 of...

 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 counting...

 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 rates for...

 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 DGTD...

 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 prove the...

 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, or in...

 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 recent...

 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 hard...

 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 groups,...

 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 leads...

 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 survey on...

 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 complexity of a...

 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 nonlocal...

 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 curves,...

 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 functions...

 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 sphere....

 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, electrons)...

 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 structures of...

 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 important...

 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 five...

 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 unique...

 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 measurements are...

 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  (independent of...

 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 upper bound...

 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 singularities, then...

 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 for which...

 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 field. The...

 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 (M,\omega).I...

 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 the...

 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 other.We...

 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 spaces...

 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, for a...

 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 composition. The...

 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 "Fer...

 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 closure...

 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 necessarily...

 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 and...

 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 is the...

 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 the...

 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 of...

 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 into play....

 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 equations in...

 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 this...

 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 also...

 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 partial...

 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 unstructured...

 Boundedness for some doubly nonlinear parabolic PDEs 2013-10-25 Speaker: Eurica Henriques (CM/UTAD) We show that, in the setting of measure spaces equipped with a doubling non-trivial Borel measure $\mu$, of dimension $d_\mu$, supporting a weak Poincaré inequality, the nonnegative weak subsolutions of the doubly nonlinear equation \$(u^{q})t-\div{(|\nabla u|^{p-2}\nabla u)}=0, ...

 Obstacle problems in variable exponent Sobolev spaces 2013-10-18 Speaker: Rafayel Teymurazyan (CMAF, Univ. Lisboa) We are going to discuss the obstacle problem for a quite large class of heterogeneous quasi-linear degenerate elliptic operators in variable exponent Sobolev spaces (Orlicz-Sobolev spaces). We see that the solution has C^{1,\alpha}_{loc} regularity for some \alpha\in (0,1) and prove that the...

 Einstein manifolds with skew torsion 2013-10-16 Speaker: Ana Cristina Ferreira (Univ. Minho) In this talk, we will present a systematic investigation of manifolds that are Einstein for a connection ∇ with skew symmetric torsion. We derive the Einstein equation from a variational principle and prove that, for parallel torsion, any Einstein manifold with skew torsion has constant scalar...

 What is a tensor product internally? 2013-10-15 Speaker: Tim Van der Linden (Université Catholique de Louvain, Belgium) When the concept of tensor product is studied from a categorical perspective, it is usually treated either as additional structure on a category - which leads to the theory of monoidal and enriched categories - or in an ad-hoc way involving free algebras of some kind. Quite surprisingly, as yet no...

 Remarks on reflexive multiplicative graphs in Gumm categories 2013-10-15 Speaker: Diana Rodelo (CMUC and Univ. Algarve) A Gumm category is a finitely complete category where the categorical version of the Shifting Lemma holds. In varieties of universal algebras, the validity of this lemma is equivalent to being congruence modular. Mal'tsev and Goursat categories give examples of Gumm categories. We show that...

 Experimental Optimization: the elephant in the room 2013-10-09 Speaker: Bunin Gene (EPFL, Lausanne, Switzerland) Experimental optimization problems, though ubiquitous in the applied sciences, are a surprisingly underdeveloped field from the theoretical perspective. In this talk, we will define a canonical experimental optimization form, show how it is a generalization of the better-known derivative-free...

 Gray codes and lexicographical combinatorial generation for nonnesting and sparse nonnesting set partitions 2013-10-09 Speaker: Alessandro Conflitti (CMUC, Univ. Coimbra) I shall discuss about combinatorial Gray codes and explicit designs of efficient algorithms for lexicographical combinatorial generation of the sets of nonnesting and sparse nonnesting set partitions of length n and type A....

 Modelação e monitorização de dados usando famílias de distribuições 2013-10-04 Speaker: Fernanda Otília Figueiredo (Fac. Economia, Univ. Porto) A utilização de famílias de distribuições na modelação de dados reais permite uma maior versatilidade na escolha do modelo que melhor se ajusta às diferentes peculiaridades dos dados. Apesar da desvantagem subjacente à necessidade de...

 A new test for multivariate normality by combining extreme and non-extreme BHEP test statistics 2013-10-04 Speaker: Carlos Tenreiro (CMUC/FCTUC) In this talk we present a new multiple test procedure for assessing multivariate normality which combines the BHEP (Baringhaus-Henze-Epps-Pulley) tests by considering extreme and non-extreme choices of the smoothing parameter figuring in the definition of the BHEP test statistic. The results of a...

 A quantitative Hölder exponent for the non-homogeneous p-parabolic equation 2013-10-04 Speaker: José Miguel Urbano (CMUC, Univ. Coimbra) That weak solutions of degenerate parabolic pdes modelled on the inhomogeneous p-Laplace equation are Hölder continuous is known for almost 30 years. What was hitherto missing from the literature was a precise and sharp knowledge of the Hölder exponent in terms of p, the integrability of...

 Hermite finite elements for fluid flow and heat transfer 2013-10-02 Speaker: Vitoriano Ruas (UPCM-Paris 6, France) Traditionally Hermite finite elements have been used to solve fourth or higher order boundary value PDE's, for in this case minimum continuity of solution derivatives must be ensured. It turns out that nothing prevents this kind of methods from being used to solve second order boundary value...

 On error control and adaptivity for convection-dominated problems 2013-09-25 Speaker: Emmanuil H. Georgoulis (Univ. Leicester, UK) Advection-dominated advection-diffusion-reaction elliptic and parabolic problems are known to be challenging numerically, due to the stiffness created by the interplay between the advection and the diffusion. In the context of ﬁnite element methods, a number of techniques which enhance the...

 A structure theorem for co-Kähler manifolds 2013-09-13 Speaker: Giovanni Bazzoni (Universität Hamburg, Germany) Co-symplectic and co-Kähler structures are the odd-dimensional analogue of symplectic and Kähler structures. In this talk we shall review the basic concepts of both geometries, which are a special case of almost contact metric structures. We will prove a structure theorem for compact...

 Double negation and other sites on monoides of sequences related to the convergence 2013-09-12 Speaker: Luis Espanol (Univ. de La Rioja, Logroño, Spain) The abstract is in the attached pdf file....

 The frame of partial reals and the Dedekind order completion of C(L) 2013-09-12 Speaker: Imanol Mozo Carollo (Univ. of the Basque Country, Bilbao, Spain) Let L(R) denote the frame of reals [1], that is, the frame generated by all ordered pairs (p,q) of rationals, subject to the relations(R1) (p,q) ^ (r,s) = (p v r, q ^ s),(R2) (p,q) v (r,s) = (p,s) whenever p <= r < q <= s,(R3) (p,q) =V{(r,s) | p < r < s < q},(R4) V{(p,q) | p,q in...

 Some basic spectral properties of complex tridiagonal matrices and the one-dimensional perturbations method. 2013-07-25 Speaker: Mikhail Tyaglov (Shanghai University, China) In the talk we give some properties of the spectrum and the root subspaces of an arbitrary complex tridiagonal matrix. We also consider the related sequences of orthogonal polynomials and study their roots. Finally, we discuss some applications of the one-dimensional perturbations method developed...

 Regularity for anisotropic fully nonlinear integro-differential equations 2013-07-12 Speaker: Raimundo Leitão (Univ. Coimbra) We consider fully nonlinear integro-differential equations governed by kernels that have different homogeneities in different directions. We derive a nonlocal version of the ABP estimate, a Harnack inequality, and interior regularity. We show the estimates are stable as the smallest degree of...

 Cliques and cut-cliques: formulations and applications 2013-07-10 Speaker: Pedro Coimbra (ISCAC, Polytechnic Institute of Coimbra) A network/graph provides an abstract representation, establishing the relationships among a set of elements. It helps organizing the information and provides an overall view of the underlying system.These structures are being used in a large number of areas and scientific domains, namely in...

 Stability of hyperfinite knots 2013-07-02 Speaker: Pedro Lopes (IST, Lisboa) A hyperfinite knot is an attempt to make sense of limits of sequences of knots with increasing crossing number.Given a knot invariant taking values on a complete metric space, we define the following quotient space of equivalence classes of knots: two knots are related if, by definition, they have...

 Free boundary problems and geometric regularity theory 2013-06-21 Speaker: Eduardo Teixeira (Univ. Federal do Ceará, Brazil) I will discuss a new geometric approach to problems related to regularity issues for elliptic and parabolic problems. Motivated by fundamental questions from the theory of free boundary problems, this new set of tools has been shown to be rather efficient in the solution of a number of...

 Choice and Pointfree Topology 2013-06-18 Speaker: Bernhard Banaschewski (McMaster Univ., Hamilton, Canada) Remarks on the interaction between pointfree topology and certain choice principles, specifically the Axiom of Choice (AC), the Axiom of Countable Choice (ACC), and the Boolean Prime Ideal Theorem (PIT), in connection with the following issues:(1) The equivalence of PIT with certain spatiality...

 A chromaticity-brightness model for imaging processing in a "u + v" framework 2013-06-14 Speaker: Rita Gonçalves Ferreira (IST/CMA) In imaging processing many important issues arise such as image segmentation, color restoration, and image denoising. A rigorous mathematical analysis is needed to validate the extensive numerical analysis literature in this field, and to open new avenues on image recolorization...

 A new look to non-Fickian diffusion 2013-06-12 Speaker: Elias Gudiño (Univ. Coimbra) In this talk a non-linear mathematical model to describe absorption phenomena in polymers is proposed. The model is established assuming that the diffusing penetrant causes a deformation which induces a stress driven diffusion and consequently a non-Fickian mass flux. We also present a...

 Formal deformations and q-deformations in stage, and Hom-algebras 2013-06-12 Speaker: Abdenacer Makhlouf (Univ. de Haute Alsace, France) In this talk I will provide two point of views for deforming algebraic structures. The first approach is formal deformations introduced by Gerstenhaber for associative algebras, using one parameter formal power series, and then extend to Lie algebras by Nijenhuis and Richardson. It will be...