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On a quadratic Schrödinger system
20170616

Speaker: Filipe Oliveira (Univ. Nova de Lisboa)

See the attached file...



Nonorientable hypermaps
20170613

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 blockradial subspaces of Sobolev and Besov spaces: regularity, decay and compactness
20170609

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
20170602

Speaker: Sonia Seyed Allaei (CMUC)

See the attached file. ...



Two mathematical approaches in ophthalmology
20170601

Speaker: Maryam Khaksar Ghalati

TBA Maryam Khaksar Ghalati is a former PhD student of the Joint PhD Program UCUP, in the area "Numerical Analysis andOptimization" under the supervision of professors Adérito Araújo and Sílvia Barbeiro. ...



Reducibility of nilpotent cone for GHiggs bundle moduli space
20170601

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
20170601

Speaker: Muhammad Ali Khan (UP student)

TBA Muhammad Ali Khan is a PhD student of the Joint PhD Program UCUP, 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
20170531

Speaker: Deividi Pansera (Univ. Porto)

See the attached file....



Singularities of noncommutative integrable systems
20170530

Speaker: Rui Loja Fernandes (Univ. of Illinois at UrbanaChampaign, USA)

Integrable systems that appear in "nature" always have singularities and there is a wellknown theory of nondegenerate singularities, which are divided into 3 classes: elliptic, focusfocus and hyperbolic classes. However, in the case of noncommutative integrable systems, such a theory...



On Besov spaces of smoothness zero
20170526

Speaker: Oscar Domínguez (CMUC)

see the attached file...



Extensions of Herstein's theory on Jordan (and Lie structures) to more general associative systems
20170524

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]=xyyx) or the Jordan product (x°y=xy+yx)....



Early exercise boundaries for Americanstyle knockout options
20170518

Speaker: José Carlos Dias (ISCTEIUL Business School)

Under mild assumptions, this paper proposes a novel representation for the early exercise boundary of Americanstyle double knockout options in terms of the simpler optimal stopping boundary of a nested single barrier Americanstyle contract. Therefore, and from now on, any singlefactor...



Characterization and estimation of the upcrossings index
20170517

Speaker: Ana Paula Martins (CMAUBI, 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
20170517

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 knottheoretic 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 TriebelLizorkin spaces
20170510

Speaker: Franka Baaske (FriedrichSchillerUniv. Jena, Germany)

See the attached file...



The \thetaparareal schemes
20170503

Speaker: Richard Tsai (Univ. of Texas at Austin, USA)

We propose a variant of the parareal method for parallelintime computation of time dependent problems. We call it the θparareal schemes because it formally resembles the θschemes for discretizing time dependent partial differential equations. We analyze the linear stability of the...



Morrey spaces on domains: different approaches and growth envelopes
20170428

Speaker: Cornelia Schneider (Univ. ErlangenNuremberg, Germany)

see the attached file...



Corecursive algebras
20170426

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 psdminimality
20170426

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 psdminimality of polytopes: A dpolytope is said to be psdminimal 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
20170419

Speaker: Zélia Rocha (CMUP, Univ. Porto)

See the attached file....



Graph complexes and configuration spaces of points
20170419

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
20170419

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?
20170419

Speaker: António Girão (Univ. Cambridge, UK)

See attached pdf file....



Fast algorithms for high frequency wave propagation
20170412

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
20170411

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
20170407

Speaker: Sergey Tikhonov (CRM, Barcelona, Spain)

TBA...



Volterra integral equations for non linear partial differential equations of integrable type
20170407

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
20170405

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 infinitedimensional Riemannian structures.Understanding the underlying geometry of a PDE immediately...



Combinatorics in minimal case completions of matrix pencils
20170405

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
20170405

Speaker: Charles R. Johnson (College of William and Mary, Williamsburg, USA)

TBA...



Resolvability of topological spaces
20170331

Speaker: István Juhász (Alfréd Renyi Inst. of Mathematics, Budapest, Hungary)

A topological space X is called λresolvable, 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
20170329

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 noncommutative 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
20170322

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
20170322

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 pointsource emission.Such quantities are investigated by means of analytical and numerical...



Nonparametric models for extreme risks with urn models
20170322

Speaker: Juerg Husler (Univ. of Bern, Switzerland)

Extreme risk is often modelled with parametric or semiparametric 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 categoricalalgebraic conditions in Sprotomodular categories
20170321

Speaker: Andrea Montoli (Università degli Studi di Milano, Italy)

We study, in the context of Sprotomodular categories, relative versions of some categoricalalgebraic conditions already considered for semiabelian categories, like the algebraic coherence and the local algebraic cartesian closedness. The goal is to obtain a hierarchy between Sprotomodular...



Interesting algebras between Kleisli and EilenbergMoore
20170321

Speaker: Lurdes Sousa (CMUC, IP Viseu)

We investigate important categories lying strictly between the Kleisli category and the EilenbergMoore category, for a KockZöberlein monad on an orderenriched 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
20170317

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
20170315

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
20170308

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
20170308

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
20170222

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
20170222

Speaker: José Augusto Ferreira (CMUC, Univ. Coimbra)

Transport processes in porous media have being described by the classical convectiondiffusion 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
20170217

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
20170215

Speaker: Pedro Martins (IPCoimbra and CMAFCIO)

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
20170215

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
20170210

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 finiteelement approximations of arbitrary order in curved domains circumventing the isoparametric technique
20170210

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 finiteelement 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
20170208

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
20170208

Speaker: Paula Carvalho (CMUP, Univ. Porto)

I will present some classes of Noetherian algebras that I have been studying regarding their representation theory; downup 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
20170203

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
20170130

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
20170130

Speaker: Thomas Laffey (Univ. College Dublin, Ireland)

See attached pdf file....



Statistical detection of some topological and geometric features
20170126

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 lowerdimensional, 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
20170126

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
20170126

Speaker: Franco Magri (Univ. degli Studi di MilanoBicocca, 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 tableauswitching involution
20170118

Speaker: Olga Azenhas (CMUC, Univ. Coimbra)

RobinsonSchensted 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 ARLunbiased ccharts for INAR(1) Poisson counts
20170113

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 prespecified incontrol average run length (ARL) and the...



The ADR algebra and other strongly quasihereditary algebras
20170104

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 finitedimensional algebra A, we may associate to it a special endomorphism algebra...



Some tools for the study of Cartan connections on proper Lie groupoids
20161216

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...



CastelnuovoMumford regularity and graph invariants
20161216

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
20161214

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 nonassociative algebras
20161214

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 nonassociative algebras. In particular, we will talk about results of...



How to centralize and normalize quandle extensions
20161213

Speaker: Mathieu DuckertsAntoine (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
20161207

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 NPhard 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
20161207

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
20161207

Speaker: Mohamed Boucetta (Univ. CadiAyyad, Marrakech, Morocco)

See attached file. ...



On locally conformal symplectic manifolds of the first kind
20161206

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
20161202

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
20161202

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
20161130

Speaker: André Oliveira (CMUP, Univ. Porto)

See attached file....



The C^{p'}regularity conjecture in the plane
20161125

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
20161123

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
20161118

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
20161118

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 supercritical exponent of smoothness....



Monoidal categorical Galois theory
20161115

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
20161115

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 pmedian on disconnected graphs
20161109

Speaker: Jorge Orestes Cerdeira (Univ. Nova de Lisboa)

The <i>p</i>median problem is a wellknown NPhard 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 TriebelLizorkin spaces with variable exponents
20161104

Speaker: Helena Gonçalves (Technische Univ. Chemnitz, Germany)

See the attached file...



A successful pair: symbolic dynamics and (pro)finite semigroups
20161104

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
20161104

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
20161028

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
20161028

Speaker: João Gouveia (CMUC, Univ. Coimbra)

Let M be a pbyq 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
20161026

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
20161025

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
20161019

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 integrodifferential, nonlinear and functionaldifferential problems, among others, have been made. Despite...



Explicit Schoen Surfaces
20161019

Speaker: Carlos Rito (Centro de Matemática da Universidade do Porto)

See the attached file....



Group theory and special functions theory: a two way street
20161019

Speaker: R. ÁlvarezNodarse (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 complexvalued once differentiable conductivities in 2D
20161014

Speaker: Evgeny Lakshtanov (Univ. Aveiro)

The classical dbarmethod 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
20161014

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
20161014

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
20161012

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
20161012

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
20160930

Speaker: Antonio Sodre (Department of Mathematics, Univ. of Texas at Austin)

Deterministic dynamics on stationary point process in R^d are built upon compatible pointshifts: translation invariant mappings from each point of the process to another. When a pointshift is applied multiple times to a pointprocess it creates a sequence of distributions, namely, the...



Saturated numerical semigroups
20160928

Speaker: Manuel B. Branco (Univ. Évora)

See the attached file....



The variable coefficients thin obstacle problem
20160923

Speaker: Wenhui Shi (CMUC)

See the attached file....



On a fractional MongeAmpère operator
20160916

Speaker: Fernando Charro (UPC, Barcelona, Spain)

See the attached file. ...



Conjecture of AlonTarsi
20160720

Speaker: Carlos Gamas (Univ. Coimbra)

See the attached file...



Monochromatic configurations in finite colorings of N
20160706

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 0Hecke monoid
20160629

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 BorelSchur algebra. This is joint...



Homotopy Excision
20160628

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
20160628

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
20160627

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...



Crossconnections of balanced categories
20160627

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 crossconnection of such categories.An extended abstract of the talk is attached herewith....



Application of the Kalman filter in the statistical modelling of time series
20160617

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 LaguerreHahn orthogonal polynomials of class one
20160617

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
20160615

Speaker: Leonardo Colombo (Univ. Michigan, USA)

Under some mild regularity conditions, optimal control problems can be understood as higherorder 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 reactionwavediffusion equation with distributed order in time
20160601

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
20160527

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
20160519

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
20160517

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
20160517

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
20160513

Speaker: Therese Mieth (FriedrichSchillerUniv. Jena, Germany)

See the attached file...



A model for phase transitions with competing terms
20160512

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 nonconvex functional of the type $$\int_\Omega f(u(x),\nabla u(x),\rho(x)) \, dx $$ as a variational model to address twophase transitions problems under...



Invariants and Hochschild cohomology of rings of differential operators in one variable
20160504

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
20160427

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 QuasiNijenhuis algebroids
20160427

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 NewlanderNirenberg 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
20160422

Speaker: Juhana Siljander (Univ. Jyväskylä, Finland)

The sharp regularity of weak solutions to the porous medium equation is a longstanding open problem. The fundamental solution of the problem, the so called Barenblatt solution, is known to be C^{1/(m1)}Hölder continuous, and it is a natural question whether this is the worst possible...



Biology and Mathematics: a strategic alliance against cancer through new antitumoral therapies
20160420

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...



MixedEffect State Space models applied to environmental data: the discrimination of the Water Quality Monitoring Sites in River Vouga
20160415

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
20160413

Speaker: Farid Bozorgnia (IST, Univ. Lisboa)

In this talk, we consider different models of ReactionDiffusion 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
20160413

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 onesizefitsall notion...



On topological semiabelian algebras
20160407

Speaker: Mathieu DuckertsAntoine (CMUC)

In this talk, we will study some aspects of the categories of topological semiabelian 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
20160406

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 TimeFrequency Analysis
20160406

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 timefrequency 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
20160401

Speaker: José Matias (IST, Lisboa)

Structured deformations provide a model to nonclassical 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
20160330

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
20160322

Speaker: Tim Van der Linden (Univ. Catholique de Louvain, Belgium)

When, in a semiabelian 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 simplicialgeometrical ideas...



The BeckChevalley property for Goursat categories
20160322

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 BeckChevalley condition, with respect to the fibration of...



The kword problem over DRG
20160310

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...



nAlgebras admitting a multiplicative basis
20160309

Speaker: José M. Sánchez Delgado (CMUC)

See the attached file....



Singular foliations and Lieinfinity algebroids
20160304

Speaker: Camille LaurentGengoux (Univ. Lorraine, France)

We will describe a natural Linfinity 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
20160226

Speaker: Oleksiy Karlovych (Univ. Nova de Lisboa)

See the attached file. ...



Nonsmooth atomic decomposition of 2microlocal spaces with variable integrability
20160219

Speaker: Helena Gonçalves (Technische Univ. Chemnitz, Germany)

The abstract is in the attached pdf file...



Besov and TriebelLizorkin spaces with variable exponents
20160218

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
20160217

Speaker: Fatemeh Esmaeili Taheri (CMUC)

See the attached file....



On a version of homological algebra in the category of semimodules and its applications
20160216

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
20160212

Speaker: Juha Videman (IST, Univ. Lisboa)

The abstract is in the attached pdf file...



Systems of PDEs in porous media
20160205

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 nonconvex structure....



The action of a 2group on a category and its application in higher gauge theory
20160201

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 2group action on a category C, and how such an action gives rise to a...



Howson's property for semidirect products of semilattices by groups
20160201

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
20160128

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
20160127

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
20160120

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
20160118

Speaker: Pierluigi Graziani (University of ChietiPescara  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
20160118

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 KleinGordon equation with HagstromWarburton highorder absorbing boundary conditions
20160118

Speaker: Ana M. Portillo (Univ. Valladolid, Spain)

KleinGordon 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 HagstromWarburton highorder absorbing boundary conditions. The space discretization is reached by means of finite differences...



An overview on the dimension of projected patterns in reactiondiffusion systems
20151217

Speaker: Juliane Fonseca de Oliveira (UPorto student)

TBA...



Tuning polymeric and drug properties in a drugeluting stent: a numerical study
20151217

Speaker: Jahed Naghipoor (ISM, BauhausUniversität Weimar, Germany)

TBA...



Change of matrix eigenvalues multiplicity associated with perturbation of a diagonal element or deletion of a row and column
20151216

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 2categories
20151215

Speaker: Benjamín Alarcón Heredia (CMA, FCTUNL)

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 2categories, so we can think of small 2categories as spaces. In this talk I will present the different ways...



The rank of variants of nilpotent pseudovarieties
20151215

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
20151209

Speaker: Ana J. João (CEMATIST, 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
20151119

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 Schrödingerlike and wave equations and in its physical derivation depends on a parameter $\alpha.$...



Analogies between optimal transport and minimal entropy
20151119

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 MongeKantorovich 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
20151113

Speaker: Graça Carita (Univ. Évora)

An integral representation result is obtained for the relaxation of a class of energy functionals depending on two vector fields u in BV and v in Lp with 1<p≤+∞. This energy have been introduced to deal with equilibria for systems depending on chemical...



The Taylor property in nonnegative autoregressive stochastic processes
20151113

Speaker: Cristina Martins (DMUC, Univ. Coimbra)

In this talk we analyse the presence of the Taylor property in linear models. Limiting the study to nonnegative 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?
20151110

Speaker: Tim Van der Linden (Université Catholique de Louvain, Belgium)

In his Ph.D.thesis [3], Nelson MartinsFerreira 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
20151110

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
20151104

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
20151104

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
20151028

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
20151027

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
20151023

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 longtime convergence results....



Rolling maps and applications
20151022

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
20151014

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
20151013

Speaker: Fernando Lucatelli Nunes (CMUC, Univ. Coimbra)

Firstly, we talk about the general result of coherence due to PowerKellyBlackwell and Lack. Then, we show how this motivates the study of a 2dimensional 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
20151013

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 releaseabsorption model for drug delivery systems
20151007

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 twophase substance between two coupled media of different properties and extents. The first...



Approximation numbers of weighted Sobolev embeddings via bracketing
20151002

Speaker: Therese Mieth (FriedrichSchillerUniv. Jena, Germany)

...



Heegaard genus and rank of link complements
20150930

Speaker: Darlan Girão (Univ. Federal Ceará, Brazil)

In this talk we will discuss the relationship between the Heegaard genus and rank of 3dimentional 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
20150929

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 timedependent Maxwell's equations in anisotropic materials for modelling light scattering in human eye's structure
20150924

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
20150909

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.
20150908

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, nonlinear ordinary differential equations and system of equations
20150724

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
20150717

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
20150709

Speaker: María José PereiraSáez (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 CWcomplex 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
20150708

Speaker: Kannappan Palaniappan (Univ. Missouri, Columbia, USA)

Visual featurebased 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
20150707

Speaker: Kannappan Palaniappan (Univ. Missouri, Columbia, USA)

Automatic segmentation of threedimensional 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 nondualizable
20150707

Speaker: Wolfram Bentz (CEMATFCUL, 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.
20150707

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 preLagrangians in toric contact manifolds
20150702

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
20150701

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
20150618

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 KieferWolfowitz algorithm under quasiassociated random errors
20150618

Speaker: Idir Arab (University of Bejaia, Algeria)

In this talk, we study the algorithm of KieferWolfowitz under quasiassociated 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
20150618

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
20150617

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 mosquitoborne viral disease in the world. According to World...



Regularity properties of maximal functions
20150608

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 onedimensional HardyLittlewood maximal operator should not increase the variation of a function. The answer for...



Linfty graded manifolds, Kapranov manifolds and applications
20150605

Speaker: Camille LaurentGengoux (Univ. Lorraine, France)

Several linearization problems can be expressed as the linearization of a Linfty 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 Newtonlike methods
20150603

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 noncommutativity of quaternion multiplication, the use of rootfinding methods involving...



On AuslanderReiten sequences for simple modules in the BorelSchur algebras
20150603

Speaker: Ana Paula Santana (CMUC/Univ. Coimbra)

I will construct AuslanderReiten sequences for a large class of simple modules over BorelSchur algebras. Partial information on the structure of the socles of BorelSchur algebras will also be given.This is joint work with Karin Erdmann and Ivan Yudin....



Eigenvalues, multiplicities and graphs: recent advances and open problems
20150601

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 nonautonomous ODEs
20150529

Speaker: António Bento (Univ. Beira Interior)

...



Primitive multiple curves: classification, moduli spaces of sheaves, deformations
20150527

Speaker: JeanMarc Drézet (Institut de mathématiques de Jussieu, France)

A primitive multiple curve is a CohenMacaulay 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...



Kaninjectivity of locales and spaces
20150519

Speaker: Lurdes Sousa (IP Viseu and CMUC)

Two wellknown 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 zeroclass of?
20150519

Speaker: Andrea Montoli (CMUC)

We characterize, in pointed regular categories, the ideals as the zeroclasses of surjective relations. Moreover, we study a variation of the ''Smith is Huq'' condition: two surjective left split relations commute as soon as their zeroclasses commute.Joint work with Nelson MartinsFerreira, Aldo...



Boundedness of Stein's spherical maximal function in variable Lebesgue space and application to the wave equation
20150515

Speaker: Amiran Gogatishvili (Czech Academy of Sciences, Czech Republic)

The abstract is in the attached pdf file...



Wavelets in Economics and Political Science
20150506

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
20150424

Speaker: Luís Daniel Abreu (ARIAustrian 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
20150422

Speaker: Luís Daniel Abreu (ARIAustrian 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
20150417

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
20150415

Speaker: José S. Antunes do Carmo (Marine and Environmental Sciences Centre/UC)

In the 80’s, numerical models based on the SaintVenant 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 nondispersive theory, of which...



Monóides de Ehresmann
20150415

Speaker: Gracinda M.S. Gomes (DMFCUL e CEMATFCUL, Univ. Lisboa)

Na teoria dos monóides inversos a classe dos próprios, ou Eunitários, tem um papel crucial, já que todo o monóide inverso tem uma cobertura própria (que separa idempotentes), um monóide inverso próprio tem ...



BorelSchur algebras of finite representation type
20150415

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 BorelSchur algebras of finite type. This is a joint work with K. Erdmann and A.P. Santana....



A Néron model of the universal jacobian
20150413

Speaker: David Holmes (Univ. Leiden, The Netherlands)

Every nonsingular algebraic curve C has a jacobian J, which is an abelian variety. Choosing a point on the curve determines an `abeljacobi' map from C to J. The same constructions can be made in families: given a family of nonsingular curves (together with a section), one obtains a family of...



An optimal design problem with fractional diffusion
20150410

Speaker: Rafayel Teymurazyan (CMUC)

We study an optimization problem ruled by afractional 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
20150408

Speaker: Miguel Patrício (Lab. Biostatistics and Medical Informatics, IBILIFMUC)

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
20150408

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 pseudoRiemannian submanifolds
20150325

Speaker: André Marques (Instituto Politécnico de Viseu)

We present an overview about rolling motions, subject to nonslip and nontwist constraints, of manifolds which are embedded in pseudoRiemannian manifolds. Within this general framework, we analyze the individual cases of rolling of pseudohyperbolic spaces and quadratic Lie groups. We address the...



Covers of the projective plane
20150325

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 precrossed modules
20150324

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 precrossed modules over a fixed object B, extending the corresponding classical notions to any semiabelian category. We prove that, under mild additional assumptions on the category, crossed modules are...



The localic group of the unit circle
20150324

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
20150318

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
20150313

Speaker: Eugénio Rocha (Univ. Aveiro)

in the attached file ...



Invariant theory and descent via symmetric monoidal categories
20150311

Speaker: Ehud Meir (Univ. Copenhagen, Denmark)

Let C be a symmetric monoidal Klinear 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_KG, of the finite dimensional rational representations of...



Modelling with clinical data: examples, limitations, aims ...
20150311

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 \DeltaToda and Volterra lattices
20150227

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
20150225

Speaker: Alan Cain (CMA, Univ. Nova de Lisboa)

In recent work with Gray and Malheiro, I proved that finiterank plactic monoids (in which Young tableaux form a crosssection) 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
20150219

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) quasiisomorphic to the algebra of differential forms. It is known that the...



Some recent mathematical ideas for applications in biology
20150211

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 PoissonNernstPlanck equations
20150206

Speaker: Léonard Monsaingeon (IST, Univ. Lisboa)

The abstract is in the attached pdf file...



On Randic spread
20150204

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
20150203

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 (selfexciting threshold) binomial AR(1) model.The Poisson INAR(1) model is the most simple...



Hexagonal projected symmetries
20150128

Speaker: Juliane Oliveira (Univ. Porto)

Threedimensional symmetries are often observed as 2dimensional objects. In this seminar we will provide a description of which 3dimensional lattices may produce 2dimensional projected pattern with hexagonal symmetries. As an application we compare some projected spatially periodic functions,...



Compactness in quasiBanach function spaces
20150123

Speaker: António Caetano (Univ. Aveiro)

The wellknown 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
20150113

Speaker: Dirk Hofmann (Univ. Aveiro)

The aim of this talk is to lift the wellknown 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 Sprotomodular categories
20150113

Speaker: Andrea Montoli (CMUC)

We study the socalled "Smith is Huq" condition in the context of Sprotomodular categories: two Sequivalence 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
20141210

Speaker: Luís Ferrás (Inst. Polímeros e Compósitos, Univ. do Minho)

In this work we present a study on flows of Newtonian and NonNewtonian 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...



Densitybased cluster analysis: an interface between Statistics, Differential Topology and Dynamical Systems
20141210

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
20141209

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. ...



KaehlerLie systems and geometric quantum mechanics
20141204

Speaker: Jesús ClementeGallardo (Univ. Zaragoza, Spain)

In this seminar we will study an application of the geometric formulation of Quantum Mechanics to study Lie systems on finitedimensional 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
20141128

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...



QuasiF frames
20141125

Speaker: Mack Matlabyana (Univ. Limpopo, South Africa)

A completely regular frame L is said to be quasiF if for every dense c ∈ CozL, the open quotient L →↓a is a C*quotient map.QuasiF frames generalize almostP frames and F'frames. The intention of the talk is to give several characterizations of these frames....



On topological semiabelian algebras: split extensions and their classifiers
20141125

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...



Biperiodic solutions to the FokkerPlanck equation and operation of Brownian motors
20141121

Speaker: Dmitry Vorotnikov (CMUC, Univ. Coimbra)

We study the unidirectional transport effect for Brownian ratchets modeled by FokkerPlancktype equations. In particular, we consider the adiabatic andsemiadiabatic limits for tilting ratchets, generic ratchets with small diffusion, and the multistate chemical ratchets. Having established a...



Hypermaps and their classifications
20141119

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 isA representation of a hypergraph (Combinatorics);A triangulation of a compact surface (Topology);A quotient of an...



Split Lie algebras and relations with weight modules
20141119

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
20141114

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
20141112

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 socalled Gcharacter 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
20141112

Speaker: Marcos Raydan (Univ. Simón Bolívar, Venezuela)

The Quadratic Finite Element Model Updating Problem (QFEMUP) concerns with updating a symmetric secondorder 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
20141105

Speaker: Raquel Coelho Guardado Simões (Univ. Lisboa)

A key way to understand triangulated categories is to look at generators. In the context of positive CalabiYau (CY) triangulated categories, such as cluster categories, the most interesting generators seem to be clustertilting objects. There are some triangulated categories which are naturally...



Extreme Value Theory for chaotic dynamics
20141031

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
20141028

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
20141028

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 orderopen, or, equivalently, open and orderclosed....



Uniform convergence of HermitePadé approximants for systems of Markov type functions
20141024

Speaker: Sergio Medina Peralta (Univ. Carlos III, Madrid, Spain)

This talk deals with simultaneous rational approximation. In particular we study HermitePadé approximants of analytic and meromorphic functions of Markov type. The central results of this work is about of convergence of type I HermitePadé approximants of a Nikishin system. In the...



The MOOD method, principle and (some) examples
20141015

Speaker: Stéphane Clain (Univ. Minho)

We present a new finite volume method to provide 6thorder 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
20141003

Speaker: Dorothee D. Haroske (Univ. Jena, Germany)

...



Computational methods in the fractional calculus of variations
20141001

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 BrillNoether theory
20141001

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 BrillNoether theorem, whose purely combinatorial proof is an open problem....



Fundamental group functors and higher Hopf formulae
20140930

Speaker: Mathieu DuckertsAntoine (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 Galoistheoretic notion of covering morphism. Using this perspective, T. Everaert, M....



Lax algebras as spaces
20140930

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
20140924

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
20140919

Speaker: Filipa Silva (CMUC)

The aim of this talk is to introduce an integervalued 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
20140919

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 lgroup
20140911

Speaker: Richard N. Ball (Univ. Denver, USA)

In this talk we develop the analog for truncated archimedean latticeordered 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 lgroups
20140910

Speaker: Richard N. Ball (Univ. Denver, USA)

We generalize the concept of the pointwise supremum of realvalued 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
20140910

Speaker: Manuel B. Cruz (LEMA/ISEP)

The interaction MathematicsIndustry has suffered a great development in the latest years. The genesis of EUMATHSIN, 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
20140910

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 (mathin) 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
20140725

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}, 591599. 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
20140723

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
20140716

Speaker: Stephen Donkin (Univ. of York, UK)

We consider the problem of determining which irreducible polynomial modules occur as a composition factor of an mfold 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...



MehlerHeine asymptotics of polynomials
20140716

Speaker: Juan J. Moreno Balcázar (Univ. Almeria, Spain)

In this talk, we will give an overview about MehlerHeine 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 paraorthogonality theory
20140716

Speaker: Kenier Castillo (UNESP, Brazil)

Our goal is to provide the paraorthogonality theory with a new powerful tool for computing: recurrence relation. Analogous results to the classicals Favard and GeronimusWendroff theorems are deduced....



Compact embeddings of weighted Sobolev spaces
20140711

Speaker: Therese Mieth (FriedrichSchillerUniv. Jena, Germany)

The abstract is in the attached pdf file ...



Kaninjectivity in Top0 and Kanprojectivity in Frm
20140710

Speaker: Margarida Carvalho (ISCAC)

In the context of categories enriched in the category of partial order sets, we will work with KZreflectivity and Kaninjectivity, 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 Kaninjective hulls...



Lax orthogonal factorisation systems
20140710

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 qAskey schemes
20140709

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 reexpressing the polynomials in the generating functions using multiparameter connection relations. The resulting...



NonFickian models for biodegradable drug eluting stents
20140709

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
20140709

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
20140702

Speaker: Leticia BrambilaPaz (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
20140625

Speaker: Paulo Antunes (CMUC)

We define hypersymplectic structures with torsion (HST) on Lie algebroids and establish a 11 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 Kaninjectivity
20140624

Speaker: Lurdes Sousa (CMUC and IP Viseu)

In an orderenriched 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 Kaninjective. 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, MarkovDyck and Property (A) shifts
20140624

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
20140623

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
20140620

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 bulkdiffusion driven nonlinear interface dynamics in irregular and unbounded domains. Typically the evolving...



Polar maps, foliations, characteristic classes
20140618

Speaker: Nivaldo Medeiros (Univ. Fluminense, Brazil)

To each hypersurface X in the projective nspace, 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
20140611

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
20140606

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 Leapfrog DG method for time domain electromagnetic wave propagation
20140604

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
20140528

Speaker: Sílvio Gama (Univ. Porto)

We discuss the nonlinear propagation of waves of short wavelength in dispersive systems and we present the simplest nonlinear shortwave dynamics: $u_{tx} = u  3 u^2$. We present an algorithm to integrate numerically this equation for periodic and nonperiodic boundary conditions. We also prove the...



Medical image processing using the image derivatives
20140523

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
20140523

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 semidefinite matrices
20140521

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
20140521

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 Mtheory
20140520

Speaker: John Huerta (CMAGDS, IST, Lisboa)

A trigroup is a tricategory with one object and all 1, 2 and 3morphisms invertible. Mtheory 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 Mtheory leads...



Pattern formation on evolving biological surfaces: the surface finite element method applied to reactiondiffusion systems
20140516

Speaker: Raquel Barreira (IP Setúbal)

The abstract is in the attached pdf file...



Semisimple Hopf algebra actions
20140507

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
20140507

Speaker: Karin Erdmann (Univ. Oxford, UK)

We consider finitedimensional modules of finitedimensional 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.
20140423

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 onedimensional case (random graphs), we may...



A parabolic Harnack inequality for a nonlocal in time diffusion equation
20140409

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
20140409

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
20140409

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
20140408

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, C1quotient maps, R* and G*quotient maps....



Normal semicontinuous functions in pointfree topology and weak cbframes
20140408

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
20140404

Speaker: Zouhair Mouayn (Univ. Coimbra)

We construct a family of generalized Bargmann transforms mapping isometrically the states Hilbert spaces of specific Hamiltonian operators onto L2eigenspaces 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 ICMIICIAM Study.
20140404

Speaker: Rudolf Strässer (J.L. Univ. Giessen, Germany & A.C. Univ. Brisbane, Australia)

The presentation will offer some results of the joint ICMIICIAMstudy 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
20140402

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 timefrequency ensembles
20140328

Speaker: Luís Daniel Abreu (ARIAustrian 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
20140328

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 paraorthogonal polynomials
20140321

Speaker: Kenier Castillo (Univ. Estadual Paulista, Sao Paulo, Brazil)

We study the zeros in connection with perturbed recurrence coefficients of polynomials satisfying a certain threeterm recurrence relation. As a particular case, we consider the Askey paraorthogonal polynomials on the unit circle, ${_2}F_1(n, a+b i; 2 a; 1z)$, $a,b \in \re$,...



Virial Theorem in Lagrangian formalism
20140319

Speaker: Patrícia Santos (CMUC/ISEC)

In this talk the geometric approach to the virial theorem in Lagrangian formalism is presented in quasivelocities, 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 Sprotomodular categories
20140318

Speaker: Andrea Montoli (CMUC, Univ. Coimbra)

We investigate the notion of pointed Sprotomodular 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
20140318

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
20140312

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
20140307

Speaker: Yannick Sire (Univ. d'AixMarseille, France)

I will describe a few recent results dealing with the AllenCahn 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
20140305

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
20140305

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 5torsion
20140226

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, selfintersection of the canonical divisor K2=3 and with 5torsion.If S is a quintic surface in P3 having 15 3divisible ordinary cusps as only singularities, then...



Bullwhips, conservation laws and 1Laplacian
20140207

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
20140205

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

Locating and identifying points as global minimizers is, in general, a hard and timeconsuming 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 derivativefree...



Combinatorial Game Theory: a survey
20140205

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
20140205

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 LaguerreSobolev expansions
20140131

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...



2Areplication and the Baby Monster
20140122

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, KacMoodyLie 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
20140110

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
20140109

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
20140109

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 SturmLiouville problems via Fer streamers
20140108

Speaker: Alberto Gil C. P. Ramos (Univ. Cambridge, UK)

We address the numerical challenge of solving SturmLiouville 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 nonstandard truncation of Fer expansions, which we call "Fer...



On closure properties of some risk aversion measures
20131217

Speaker: Nuria TorradoRobles (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
20131206

Speaker: Edmundo Huertas Cejudo (CMUC, Univ. Coimbra)

For a symmetric sequence of type II multiple ortogonal polynomials satisfying a highterm 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
20131204

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, noncommuting symmetric functions and set partition combinatorics
20131127

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 superrepresentation theory of the finite unitriangular group has a...



Financial risk measures
20131126

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
20131122

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
20131120

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 multiscale phasefield model that combines the benefits of continuum physics description and the capability of...



Codes over a weighted torus
20131113

Speaker: Jorge Sentieiro Neves (CMUC, Univ. Coimbra)

We will describe a new family of linear codes, extending the notion of projective generalized ReedMuller codes to a setting where the grading of the polynomial ring is nonstandard. 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
20131108

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 weakapproximate fixed point property
20131108

Speaker: Cleon Barroso (UFC, Brazil)

In this talk we will present a research line known as weakapproximate 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.
20131106

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
20131106

Speaker: Jesús ClementeGallardo (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
20131030

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 nondissipative DGTD method for timedomain electromagnetics
20131029

Speaker: Stéfane Lanteri (INRIA Sophia AntipolisMéditerranée)

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
20131025

Speaker: Eurica Henriques (CM/UTAD)

We show that, in the setting of measure spaces equipped with a doubling nontrivial 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^{p2}\nabla u)}=0, ...



Obstacle problems in variable exponent Sobolev spaces
20131018

Speaker: Rafayel Teymurazyan (CMAF, Univ. Lisboa)

We are going to discuss the obstacle problem for a quite large class of heterogeneous quasilinear degenerate elliptic operators in variable exponent Sobolev spaces (OrliczSobolev 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
20131016

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?
20131015

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 adhoc way involving free algebras of some kind. Quite surprisingly, as yet no...



Remarks on reflexive multiplicative graphs in Gumm categories
20131015

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
20131009

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 betterknown derivativefree...



Gray codes and lexicographical combinatorial generation for nonnesting and sparse nonnesting set partitions
20131009

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
20131004

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 nonextreme BHEP test statistics
20131004

Speaker: Carlos Tenreiro (CMUC/FCTUC)

In this talk we present a new multiple test procedure for assessing multivariate normality which combines the BHEP (BaringhausHenzeEppsPulley) tests by considering extreme and nonextreme choices of the smoothing parameter figuring in the definition of the BHEP test statistic. The results of a...



A quantitative Hölder exponent for the nonhomogeneous pparabolic equation
20131004

Speaker: José Miguel Urbano (CMUC, Univ. Coimbra)

That weak solutions of degenerate parabolic pdes modelled on the inhomogeneous pLaplace 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
20131002

Speaker: Vitoriano Ruas (UPCMParis 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 convectiondominated problems
20130925

Speaker: Emmanuil H. Georgoulis (Univ. Leicester, UK)

Advectiondominated advectiondiffusionreaction 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 coKähler manifolds
20130913

Speaker: Giovanni Bazzoni (Universität Hamburg, Germany)

Cosymplectic and coKähler structures are the odddimensional 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
20130912

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)
20130912

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 onedimensional perturbations method.
20130725

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 onedimensional perturbations method developed...



Regularity for anisotropic fully nonlinear integrodifferential equations
20130712

Speaker: Raimundo Leitão (Univ. Coimbra)

We consider fully nonlinear integrodifferential 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 cutcliques: formulations and applications
20130710

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
20130702

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
20130621

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
20130618

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 chromaticitybrightness model for imaging processing in a "u + v" framework
20130614

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 nonFickian diffusion
20130612

Speaker: Elias Gudiño (Univ. Coimbra)

In this talk a nonlinear 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 nonFickian mass flux. We also present a...



Formal deformations and qdeformations in stage, and Homalgebras
20130612

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...



Nonpointed additive category
20130604

Speaker: Dominique Bourn (U. Littoral, Calais, France)

The talk will deal with the study of the different degrees of nonpointed additiveness between Naturally Mal'cev categories (when the fibers of the fibration of points are additive) and essentially affine ones (when any change of base functor with respect with the same fibration is an equivalence of...



3 ×3 matrices with a flat portion on the boundary of the numerical range
20130529

Speaker: Fatemeh Esmaeili Taheri (PhD student)

In recent years, many studies have been done on the numerical range of matrices and bounded operators. In this presentation, the set of unitarily irreducible complex 3 ×3 matrices whose numerical range has a flat portion will be explicitly described and it will show that this set is connected...



A bijection for the convolution of central binomial coefficients
20130529

Speaker: Rui Duarte (Univ. Aveiro)

All known bijective proofs for the convolution of central binomial coefficients $\sum_{i+j=n} \binom{2i}{i} \binom{2j}{j} = 4^n$,are based, with some variations, on the count of lattice paths. In this talk we give a new proof of this identity, where $\binom{2 \ell}{\ell}$ is regarded as the number...



On trace spaces of 2microlocal TriebelLizorkin spaces with variable integrability
20130529

Speaker: Helena Gonçalves (PhD student)

In this seminar we study the traces of 2microlocal TriebelLizorkin spaces with variable integrability on hyperplanes. Following [2], we present the definition and properties of those spaces, in particular the characterization by atomic decomposition and embedding assertions, needed to prove the...



Some semigrouptheoretic aspects of Rauzy graphs of subshifts
20130522

Speaker: Alfredo Costa (CMUC/Univ. Coimbra)

Symbolic dynamical systems, also called subshifts, correspond in a natural way to factorial prolongable languages. In this context, it is often relevant to study factor graphs, sometimes called Rauzy graphs, to which one gives a natural automaton structure. In this talk we first discuss the problem...



Categories of lax algebras: a first approach
20130522

Speaker: Pier Giorgio Basile (PhD student)

Following the paper of M.M. Clementino and D. Hofmann [2], and having as starting point Barr's description of topological spaces as lax algebras for the ultrafilter monad [1], I am going to present the categories of lax algebras. They represent a suitable generalization of the relational algebras...



Weak solvability of one model of dynamics of thermoviscoelastic continuous medium with regularized objective Jaumann derivative
20130517

Speaker: Victor Zvyagin (Voronezh State Univ., Russia)

In the talk, we establish the weak solvability of the initial–boundary value problem for the model of dynamics of thermoviscoelastic continuous medium which rheological relations (constitutive laws) contains regularized objective Jaumann’s derivative. The investigation is carried out by...



Structures on line bundles  The deRham and Dolbeault grupoids
20130515

Speaker: Artur Araújo (PhD student)

Brief introduction to connections and complex structures on a trivial line bundles. Deformation theories; the action of gauge transformations, and the deRham grupoid. Holomorphic structures on a line bundle, and relation to connections. Higgs fields, and the Dolbeault grupoid. Equivalence of the...



Every prespectrum represents a homology theory
20130515

Speaker: Fernando Lucatelli (PhD 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...



Riesz and Wolff potentials in variable exponent Lebesgue spaces
20130510

Speaker: Alexandre Almeida (Univ. Aveiro)

We study mapping properties of Riesz and Wolff potentials in Lebesgue spaces with variable exponent. Our approach includes the limiting case corresponding to potentials of L1 functions. This case is particularly interesting in the study of some nonlinear PDEs. ...



Classification of quadratic Lie algebras of low dimension
20130430

Speaker: Said Benayadi (Univ. de Lorraine, France)

In this talk we give the classification of the irreducible non solvable Lie algebras of dimension less than or equal to 13 with nondegenerate, symmetric and invariant bilinear forms....



On the structure of graded Leibniz algebras
20130430

Speaker: José M. Sánchez Delgado (Univ. Malaga, Spain)

We study the structure of graded Leibniz algebras with arbitrary dimension and over an arbitrary base field. We show that any of such algebras with a symmetric Gsupport is the sum of a subspace of L_1 (the homogeneous component associated to the unit element 1 in G) with a family of I_j, a well...



(1,1)Coherent pairs on the unit circle
20130426

Speaker: Natalia Camila Pinzón Cortés (Univ. Carlos III, Madrid, Spain)

see file...



Modular classes and Dirac structures
20130424

Speaker: Raquel Caseiro (CMUC/Univ. Coimbra)

We begin by reviewing some properties concerning modular classes in Poisson and Lie algebroid theory. By generalizing modular classes to Dirac structures, we have a general framework to understand these structures and the reduction example of a Poisson manifold become more clear....



Quaternion arithmetic: factorization and geometry
20130417

Speaker: António Machiavelo (CMUP/Univ. Porto)

The ring of the so called Hurwitz integers, which contains the integral quaternions, being both a left and a right PID, is the appropriate ring inside the quaternions in which to study arithmetical questions. The fact that it is a non commutative ring entails some complications, but also some...



On quasiétale quotients of products of two curves
20130417

Speaker: Roberto Pignatelli (Univ. degli studi di Trento, Italy)

I will consider finite groups acting on the products of two complex algebraic curves freely out of a finite set of points. Geometrically, this means that the map onto the quotient is quasiétale. I will describe some results obtained in the last few years by several authors including myself,...



Sylvester equations for LaguerreHahn orthogonal polynomials on the real line
20130412

Speaker: Maria das Neves Rebocho (Univ. Beira Interior/CMUC)

The main purpose of the talk is to introduce matrix Sylvester differential equations in the study of LaguerreHahn orthogonal polynomials.It is shown an equivalence between the scalar Riccati differential equation for the Stieltjes function and matrix Sylvester differential equations for matrices...



On Besov and TriebelLizorkintype spaces
20130411

Speaker: Susana Moura (CMUC/Univ. Coimbra)

We give a survey on Besov and TriebelLizorkin spaces, from classical to 2microlocal spaces with variable integrability. Embeddings and traces will be considered....



Coherent states quantization and formulae for the Berezin transform
20130405

Speaker: Zouhair Mouayn (Univ. Sultan Moulay Slimane, Morocco)

We are concerned with bound states eigenspaces of the Schrodinger operator with magnetic field in Cn and in the complex unit ball Bn. We construct for each of these spaces a set of coherent states to apply a coherent states quantization method. This provides us with another way to recover the...



Infinitesimally injective polynomial modules
20130403

Speaker: Steve Donkin (Univ. of York, UK)

Working over a field of positive characteristic, we consider the problem of describing, by highest weight, the injective polynomial injective modules for the general linear group GL(n) which are also injective as restricted modules for the general linear Lie algebra gl(n). This is equivalent to...



Experiments with numerical semigroups
20130403

Speaker: Manuel Delgado (CMUP/Univ. Porto)

A set of natural numbers that is closed under addition and whose complement in the set of non negative integers is finite is said to be a numerical semigroup. The number of positive integers not belonging to a numerical semigroup is said to be its genus. Question: How many numerical semigroups of a...



On the BeckChevalley condition for Setmonads
20130326

Speaker: Maria Manuel Clementino (CMUC/Univ. Coimbra)

TBA...



Automatic presentations for algebraic and combinatorial structures
20130320

Speaker: Alan J. Cain (Univ. Porto)

An automatic presentation (also called an FApresentation) is a description of a relational structures using regular languages. The concept of FApresentations arose from computer scientists' need to extend finite model theory to infinite structures. Informally, an FApresentation consists of a...



An introduction to Sasakian geometry
20130320

Speaker: Antonio De Nicola (CMUC)

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. Finally, I will present the notions of normality and compatible metric in an...



Stability of heteroclinic networks
20130319

Speaker: Sofia Castro (Fac. Economia, Univ. Porto)

Invariant sets are important objects in the study of dynamical systems since they allow us to describe families of trajectories/solutions. In fact, a solution starting in an invariant set will remain in this set for all time. Whether this solution is complex or simple...



Fickian diffusion versus non Fickian diffusion in porous media
20130313

Speaker: José Augusto Ferreira (CMUC/Univ. Coimbra)

Traditionally, diffusion process in porous media are described by convectiondiffusionreaction equations established using Fick's law for the mass flux. Such equations give accurate results in laboratory environment for perfectly homogeneous media. Nevertheless when nonhomogeneous media are...



Derivatives of functions of matrices
20130306

Speaker: Pedro J. Freitas (Univ. Lisboa)

There have been recent results concerning directional derivatives, of degree higher than one, for the determinant, the permanent, the symmetric and the antisymmetric power maps, by R. Bhatia, P. Grover and T. Jain. We present generalizations of these results for immanants and other symmetric...



A Cauchy kernel expansion and Fomin's growth diagrams.
20130227

Speaker: Aram Emami (CMUC)

We give a bijective proof of a Lascoux's Cauchy kernel expansion over Ferrers shapes, in two families of Demazure operators. The proof is given in the framework of Fomin's growth diagrams for generalized RobinsonSchenstedKnuth correspondences, in our case, to obtain pairs of semiskyline augmented...



Dirac structures
20130227

Speaker: Raquel Caseiro (CMUC/Univ. Coimbra)

Dirac structures were introduced by T.Courant and A. Weinstein as a way to unify presymplectic and Poisson geometry. We intend to present the basics of Dirac structures, including main geometric features and key examples. First we introduce linear Dirac structures and then we generalize to smooth...



Special completions of semilattices and lattices
20130226

Speaker: Maria João Gouveia (Univ. Lisboa)

Canonical extensions of (bounded) lattices have been extensively studied, and the basic existence and uniqueness theorems for these have been extended to general posets. In this talk we will consider profinite completions of semilattices which may be identified with the iterated filter completion...



Sublattices of associahedra and permutohedra equations satisfied by associahedra
20130226

Speaker: Luigi Santocanale (Univ. de Provence, France)

The set of permutations on nelements is a poset when endowed with weak Bruhat ordering. Actually, this poset is a lattice since each finite subset of permutations has both a supremum and infimum. Such a lattice is known as the Permutohedron on nelements. A strictly related lattice is...



Zero behavior of certain perturbed ortogonal polynomials
20130222

Speaker: Edmundo Huertas Cejudo (Univ. Coimbra)

This talk is focused in the so called canonical spectral transformations of measures. We analyze the behaviour of zeros of MOPS associated with the Christoffel and Uvarov transformations of the measures. First, we introduce the representation of the perturbed MOPS in terms of the initial ones and...



HomLie algebroids
20130220

Speaker: Joana Teles (CMUC/Univ. Coimbra)

We review some definitions and constructions of homLie algebras, homassociative algebras and homPoisson algebras. We define homLie algebroids, a definition that may seem cumbersome at first, but which is justified, first, by a onetoone corespondence with homGerstenhaber algebras, a notion...



A short introduction to Coxeter systems through combinatorics of words
20130220

Speaker: Alessandro Conflitti (CMUC/Univ.Coimbra)

We give an introduction to abstract Coxeter systems using a combinatorial approach based on words, thus avoiding all the original geometric framework. The talk will be self contained, assuming no previous knowledge or background, save for very basic algebra....



Eigenvalue complementarity problem: applications and algorithms
20130220

Speaker: Luís Merca Fernandes (IP Tomar/IT)

The Eigenvalue Complementarity Problem (EiCP) finds important applications in different areas of science and engineering and differs from the traditional Eigenvalue Problem on the existence of nonnegative constraints on its variables and complementarity constraints between pairs of variables. In...



Regularity for some doubly nonlinear evolutionary equations in measure spaces
20130201

Speaker: Rojbin Laleoglu (CM, Univ. TrásosMontes e Alto Douro)

We will consider the regularity question for the nonnegative weak solutions of certain doubly nonlinear parabolic equations falling into a very large and important class of equations, namely the class of degenerate and singular equations. These type of evolutionary equations appear in the modeling...



Monochromatic Krdecompositions of graphs
20130123

Speaker: Teresa Maria Jerónimo Sousa (Univ. Nova de Lisboa)

Given graphs G and H, and a colouring of the edges of G with k colours, a monochromatic Hdecomposition of G is a partition of the edge set of G such that each part is either a single edge or forms a monochromatic graph isomorphic to H. Let $\phi_{k}(n,H)$ be the smallest number t, such that , any...



On Alexander's Subbase Lemma
20130115

Speaker: Dirk Hofmann (U. Aveiro)

Alexander's Subbase Lemma (due to James Waddell Alexander II) is a classical result of topology stating that a topological space X is compact provided that X is compact with respect to a subbasis, that is, every subbasic cover of X has a finite subcover. In this talk we will give a very simple...



Linear potentials in nonlinear potential theory
20130104

Speaker: Tuomo Kuusi (Aalto Univ., Helsinki, Finland)

We give an update to some aspects of the theory for solutions to nonlinear elliptic or parabolic, possibly degenerate, equations involving pLaplacean type operators and datum, which, in full generality, can be a measure. The main focus is to describe recent pointwise potential estimates for...



On multiobjective sequence alignment: formulation and algorithms
20121219

Speaker: Maryam Abbasi (DEI, Univ. Coimbra)

Sequence alignment is used to identify regions of similarity that may indicate functional, structural and/or evolutionary relationships between two or more biological sequences. Usually, the quality of an alignment is given by a score function that is a weighted sum of several components, such as...



Schreier graphs of selfsimilar groups
20121212

Speaker: Daniele D'Angeli (Univ. TrásosMontes e Alto Douro)

Selfsimilar groups are described as groups acting by automorphisms on a rooted tree and have been used to find examples of groups with special and exotic properties. Schreier graphs naturally appear in this context as orbital graphs of the action on the levels of the tree. In this talk I will...



Modeling nonFickian diffusion processes
20121212

Speaker: Elias Gudiño (CMUC)

An important problem in controlled release technology is the diffusion of a penetrant into a polymeric carrier where a drug is dispersed. A suitable choice for simulating drug delivery can be the classical Fick’s law. However to model the sorption of the liquid agent an equation that takes...



Instantons on the manifolds of Bryant and Salamon
20121205

Speaker: Andrew Clarke (IME/USP, Brazil)

The first examples of complete manifolds of holonomy G2 were constructed by Bryant and Salamon in the 1980's. More recently, gauge theory on manifolds on reduced holonomy has be introduced and greatly developed. I will explain this theory in the case of G2 holonomy and explain a new construction of...



Representations and combinatorics related to the Weyl algebra
20121205

Speaker: Samuel Lopes (Univ. Porto)

We consider the multiplication and differentiation operators x and d/dx, which generate the Weyl algebra. Fix a nonzero polynomial h=h(x) and let y be the operator h.d/dx, so that x and y satisfy the commutation relation [y, x]=h. The algebra generated by x and y is denoted by A_h and is a...



KAM and presymplectic dynamics
20121205

Speaker: Hassan Alishah (IST, Lisboa)

Classical KolmogrovArnoldMoser theory studies stability problem for invariant tori for nearly integrable dynamical systems. This theory has been developed beyond nearly integrable systems. I will explain basic concepts and results of the classical KAM theorem. Then I will state a KAM theorem for...



Multiscale analysis in hydrodynamics
20121128

Speaker: Sílvio Gama (Univ. Porto)

This seminar will start with a brief introduction to multiscale techniques. Afterwards, we will use these techniques to derive the large scale transport coefficients (eddy viscosity tensor included), as well as the equations that govern the largescale dynamics. Time permitting, some results will...



Algebras, monoidal structures and cocycles
20121127

Speaker: Dimitri Chikhladze (CMUC)

TBA...



Dirichlet problem in a domain with a small hole
20121123

Speaker: M. Dalla Riva (CIDMA, Univ. Aveiro)

We consider a Dirichlet problem in a domain with a small hole of diameter proportional to a real parameter $\epsilon$ and we denote by $u_\epsilon$ the corresponding solution. We show that the behavior of $u_\epsilon$ for $\epsilon$ small and positive can be described in terms of real analytic...



Vector bundles over Lie groupoids and Lie algebroids
20121121

Speaker: Matias del Hoyo (IST, Lisboa)

In a real vector space addition is settled by scalar multiplication. This makes possible to describe smooth vector bundles as manifolds endowed with a nice action of the multiplicative monoid of the real numbers. In this talk I will deal with vector bundles over Lie groupoids and algebroids. Lie...



Recent developments in matrix pencils completion problems
20121121

Speaker: Marija Dodig (CELC, Univ. Lisboa)

In this talk we shall present some new results on matrix pencil completions. The common point of all of them is a purely combinatorial problem involving triples of partitions. We shall show a solution to the combinatorial problem and give various examples of its applications to matrix...



On differencedifferential equations for deformed LaguerreHahn orthogonal polynomials on the unit circle
20121109

Speaker: Amílcar Branquinho (CMUC, Univ. Coimbra)

In this talk we study sequences of orthogonal polynomials on the unit circle whose Carathéodory function satisfies a Riccatitype differential equation with polynomial coefficients. We deduce discrete Lax equations which lead to difference equations for the corresponding sequences of...



A meeting point between matroid and representation theory
20121107

Speaker: Inês Legatheaux Martins (CELC, Univ. Lisboa)

In this talk, we introduce a matroid invariant known as the rank partition which was defined by J. A. Dias da Silva in 1990. For matroids realizable over the complex numbers, following recent work of A. Berget, we explain how this concept relates matroid theory to the representation theory of the...



Mathematical models for the simulation of organic optoelectronic devices
20121031

Speaker: Luís Morgado (Univ. TrásosMontes e Alto Douro)

Organic semiconductors, and in particular the polymeric, are of enormous interest for highvolume and lowcost manufacturing electronics industry, generally referred to as “printed electronics”. Considering that the first organic lightemitting device (OLED) based on low molecular weight...



A nonpolynomial collocation method for fractional differential equations
20121031

Speaker: Maria Luísa Morgado (Univ. TrásosMontes e Alto Douro)

In this work we are concerned with the numerical approximation of fractional differential equations. We will focus on initial and terminal value problems for ordinary differential equations of noninteger order. The approach used is based on the equivalence between this kind of...



Variational models for image segmentation
20121026

Speaker: Juan Carlos Moreno (CMUC)

In imaging science, texture and multiphase image segmentation are two problems of great interest. The importance of image segmentation models lies in looking for the best representation of an image into meaningful information by partitioning it into well distinguished regions containing some...



On a family of logconcave symmetric unimodal polynomials.
20121024

Speaker: José Agapito Ruiz (FC, Univ. Lisboa)

I will show the construction of an interesting family of polynomial sequences out of a suitable expansion of powers of the monomial (xr Ds), where x stands for multiplication by x and D is the usual derivative operator. Two wellknown members of this family are the Eulerian polynomials and the...



Matrix operations of almost linear complexity for computing eigenpairs of large dimensional problems
20121024

Speaker: Paulo Vasconcelos (CMUP)

We consider the numerical solution of a large eigenvalue problem resulting from a nite rank discretization of an integral operator. We are interested in computing a few eigenpairs, with an iterative method, so a matrix representation that allows for fast matrixvector products is required....



Primitive Groups are rare (but useful)
20121017

Speaker: Daniel Pinto (CMUC, Univ. Coimbra)

A hypermap is, in its topological form, a cellular embedding of a connected hypergraph. Hypermaps can be modified by some operations, like duality (the operation that interchanges hypervertices and hyperfaces on oriented hypermaps). The notion of duality index was created to measure how far a...



Asymptotic behaviour of a class of regular maps
20121017

Speaker: António João Breda D'azevedo (Univ. Aveiro)

Regular maps are triples $(G,a,b)$ consisting of a group $G$ and a pair $(a,b)$ of generators of $G$ (in fact a conjugacy class) being the product $ab$ an involution. A regular map ${\cal M}=(G,a,b)$ is reflexible or chiral according as $\cal M$ is isomorphic or not to its mirror image...



Regularity and geometric estimates for minima of discontinuous and singular functionals
20121012

Speaker: Raimundo Leitão (Univ. Coimbra)

This work consists of two parts: In the first part we study nonnegative minimizers of degenerate elliptic functionals for variational kernels that are discontinuous. The EulerLagrange equation is therefore governed by a nonhomogeneous, degenerate elliptic equation with free boundary between the...



Smoothing and worstcase complexity for directsearch methods in nonsmooth optimization
20121010

Speaker: Nima Garmanjani (Univ. Coimbra)

For smooth objective functions it has been shown that the worstcase cost of directsearch methods is of the same order as the one of steepest descent. Motivated by the lack of such a result in the nonsmooth case, we propose, analyze, and test a class of smoothing...



A derivativefree optimization algorithm with subspace technique
20121003

Speaker: Zaikun Zhang (Univ. Coimbra)

We will talk about optimization algorithms that do not use derivatives, namely, derivativefree algorithms. We discuss how to incorporate subspace techniques into this type of algorithms, and present a new derivativefree algorithm with subspace techniques. For the new algorithm, we...



An heterogeneous multiscale method for Aberrant Crypt Foci dynamics
20120928

Speaker: Giuseppe Romanazzi (CMUC)

Assuming that Aberrant Crypt Foci (ACF) in the colon are consequence of accumulation of abnormal cells we will characterize the dynamics of these cells, in order to describe the evolution of ACF. The colon will be considered as a periodic spread structure composed by a crypt and a...



Presentation of differentialalgebraic systems with delays (DAD) and applications of fractional derivatives to DAD systems
20120926

Speaker: Zbigniew Zaczkiewicz (Politechnika Bialostocka, Poland)

TBA...



Higher analogues of symplectic fibrations
20120919

Speaker: Olivier Brahic (IMPA, Rio de Janeiro, Brazil)

Given a differential form defined on the total space of a fibration, we interpret geometrically the equations for it to be closed. We obtain this an elementary model for higher TFTs, that can be interpreted as parallel transport along surfaces, volumes... Starting from hamiltonian fibrations,...



Geometric semiabelian categories
20120718

Speaker: George Janelidze (U. Cape Town, South Africa)

TBA...



Normalizers and algebraic exponentiation
20120718

Speaker: James Gray (UNISA, Pretoria, South Africa)

We recall the definition of algebraic exponents and their relationship to centralizers. We show that for action accessible categories the existence of normalizers implies that the category is fiberwise algebraically cartesian closed....



FEM solutions of some Boussinesqtype models for surface water waves
20120711

Speaker: Nuno Lopes (CMAF, Univ. Lisboa)

A class of improved Boussinesqtype models to simulate the propagation and generation of nonlinear dispersive waves is presented. The models are derived in order to keep some dispersive characteristics of higherorder ones. Some stability properties of the numerical models are discussed. To...



Local Hölder continuity for doubly nonlinear parabolic equations
20120629

Speaker: José Miguel Urbano (CMUC/Univ. Coimbra)

We give a proof of the Hölder continuity of weak solutions for the doubly nonlinear parabolic equation in the degenerate case. The analysis discriminates between large scales, for which a Harnack inequality is used, and small scales, that require intrinsic scaling ...



Dualities via splitting idempotents
20120628

Speaker: Dirk Hofmann (U. Aveiro)

In 1994, R. Rosebrugh and R. Wood showed that the category of complete distributive complete lattices and suprema preserving maps is equivalent to the idempotent split completion of the category of sets and relations; and ten years later they observed that this result is not really about...



Even surfaces with genus 4 and bigenus 13
20120627

Speaker: Roberto Pignatelli (Università degli studi di Trento, Italy)

In the study of algebraic surfaces, the surfaces of general type form the biggest and most mysterious class. There is no hope to get a complete classification of them but some interesting results can be obtained by fixing some (topological and birational) invariants: the most important are the...



Interpolation of uniformly absolutely continuous operators
20120622

Speaker: Bohumir Opic (Charles Univ., Prague, Czech Republic)

We develop a method suitable for interpolation of uniformly absolutely continuous operators. We apply this method to establish compactness of operators and embeddings especially in the limiting situations, where the classical interpolation methods fail. We study types of certain interpolation...



On the separability of clusters
20120620

Speaker: Jorge Orestes Cerdeira (ISA/UTL)

Separability of clusters is an issue that arises in many different areas, and is often used in a rather vague and subjective manner. We introduce a combinatorial notion of interiority to derive a global view on separability of a set of entities. We develop this approach further to evaluate...



Towards a virtual retina  a multidisciplinary approach
20120620

Speaker: Miguel Morgado (IBILI/DFUC)

...



Sampling in 2D: specificities, difficulties and applications
20120620

Speaker: José Manuel Rebordão (DF/FCUL)

Sampling strategies are a fundamental part of any measurement process. In the signal framework (onedimensional, 1D  usually the time), sampling is a wellcontrolled process. For two (images, 2D) and three (volumes, 3D) spatial dimensions, one is frequently faced with unknown objects or objects...



Multivariate Sobolev orthogonal polynomials on the ball
20120615

Speaker: Miguel Piñar (Univ. Granada, Spain)

Multivariate orthogonal polynomials associated with a Sobolevtype inner product, that is, an inner product defined by adding the evaluation of derivatives at several points to a measure, are studied. Orthogonal polynomials and kernel functions associated with this new inner product can be...



The kinematic reduction and HamiltonJacobi equation on skew symmetric algebroids
20120612

Speaker: María Barbero Liñán (Univ. Carlos III, Madrid, Spain)

HamiltonJacobi theory has strong similarities with kinematic reduction by means of decoupling vector fields of nonholonomic mechanical control systems. We describe that interconnection on a geometric structure called skewsymmetric algebroid, which generalizes the notion of ...



Hypersymplectic structures on Courant algebroids
20120612

Speaker: Paulo Antunes (CMUC/Univ. Coimbra)

In this talk, we define hypersymplectic structures on Courant algebroids and show that we recover, as particular cases, all the classical results and examples of hypersymplectic structures on Lie algebroids. As on Lie algebroids, we prove a 11 correspondence theorem between hypersymplectic...



Receiver Operator Characteristic Curves in the evaluation of medical diagnosis
20120606

Speaker: Pedro Oliveira (Instituto de Ciências Biomédicas Abel Salazar, Univ. Porto)

The origin of Receiver Operating Characteristic (ROC) analysis can be traced to the theory of statistical decision making, related to applications in signal detection and psychology and, over the years, has become a powerful tool for measuring diagnostic tests performance in medicine. A diagnostic...



Riemann Hilbert problems on a Riemann surface and on the complex plane
20120525

Speaker: Maria Teresa Malheiro (Univ. Minho)

We study the solvability of scalar RiemannHilbert problems relative to a contour on a torus which are equivalent to some matrix RiemannHilbert problems in the complex plane. With this purpose a new concept of meromorphic factorization in the torus is introduced and discussed. The results are...



Strong discontinuities in the scope of the discrete crack approach
20120523

Speaker: Daniel Dias da Costa (Univ. Coimbra)

The use of the discrete crack approach and Nonlinear Fracture Mechanics opened the possibility of accurately modelling fracture behaviour of quasibrittle materials, such as concrete, mortar and masonry. In this approach, it is assumed that microcracking localises into a surface of discontinuity,...



Endomorphism algebras of some modules for Schur algebras and representation dimension
20120516

Speaker: Stephen Donkin (University of York, UK)

This is joint work with H. Geranios. In a recent paper Miemietz and Oppermann show that, for fixed n\geq 2, the representation dimension of the Schur algebra S(n,r) goes to infinity with r, under certain characteristics restrictions. We show that this the result is valid without characteristic...



Quadratic symplectic Lie superalgebras and Lie bisuperalgebras
20120515

Speaker: Elisabete Barreiro (CMUC/Univ. Coimbra)

Lie bisuperalgebras arise in the theory of quantum mechanical integrable models and are related to the graded classical YangBaxter equation. By a triangular Lie bisuperalgebra we mean a Lie bisuperalgebra which comultiplication comes from an even skewsymmetric solution of the classical...



Integral affine geometry of noncommutatively integrable Hamiltonian systems
20120515

Speaker: Daniele Sepe (IST, Lisboa)

In mechanics there are many Hamiltonian systems which admit more integrals of motion (with suitable properties) than degrees of freedom (e.g. the Euler top). These systems are known as superintegrable or noncommutatively integrable and have been studied extensively since the pioneering work of...



Hausdorff dimension of functions on dsets
20120511

Speaker: António Caetano (Univ. Aveiro)

The sharp upper bound for the Hausdorff dimension of the graphs of the functions in Holder and Besov spaces (in this case with integrability p\geq 1) on fractal dsets is obtained: \min\{d+1s,d/s\}, where s\in(0,1] denotes the smoothness parameter. In particular, when passing from d\geq s to...



Existence results for nonNewtonian viscous fluid problems with different types of dissipation
20120427

Speaker: Hermenegildo Borges de Oliveira (Univ. Algarve/CMAF)

This seminar aims to investigate the existence of weak and very weak solutions for generalized NavierStokes problems. We will consider different problems that govern distinct flows of incompressible and homogeneous viscous fluids. The analysis will be made mainly for the versions of these...



An agency for Mathematics in interaction with enterprises and society in France
20120426

Speaker: Christophe Prud'homme (Univ. Grenoble, France)

I will discuss the creation and the first year of existence of the french Agency for Mathematics in Interaction with Enterprises and Society (AMIES) [1]. First I start with the context in which the agency was funded then I present the organisation, its objectives and the tools it provides to the...



Mal'cev products and the locality of pseudovarieties of semigroups
20120424

Speaker: Ana Paula Escada (CMUC/Univ. Coimbra)

The global of a pseudovariety of semigroups V is the smallest pseudovariety of semigroupoids which contains V, where members of V are viewed as onevertex semigroupoids. When the global of the pseudovariety V is characterized by properties of the local semigroups of its semigroupoids, the...



De Morgan algebras: new perspectives and applications
20120418

Speaker: H.P. Sankappanavar (State University of New York/CAUL)

It is well known that Boolean algebras can be defined using only the implication and the constant 0. It is, then, natural to ask whether De Morgan algebras can also be characterized using only a binary operation (implication) > and a constant 0. In this lecture, I give an affirmative answer to...



Pairs of compatible tensors on Courant algebroids and hierarchies
20120417

Speaker: Joana Nunes da Costa (CMUC/Univ. Coimbra)

We show that a PoissonNijenhuis structure can be defined on a Courant algebroid as a pair of compatible tensors satisfying several constraints. Other pairs of compatible tensors such as deformingNijenhuis and Nijenhuis pairs can also be considered. We construct natural hierarchies of such...



Deformations of Lie groupoids
20120417

Speaker: João Nuno Mestre (Utrecht University)

Deformations of Lie groupoids can be studied by means of the intrinsiccohomology that controls them. This approach is related both to thestudy of deformations of Lie group actions by Palais, and to thelinearization theorem for proper Lie groupoids. We obtain a vanishingresult for the deformation...



On polynomial sequences associated to the classical linear functionals and to second order forms
20120413

Speaker: Ana Filipa Loureiro (CMUP)

Polynomial sequences generated by integral powers of first and second order differential operators with polynomial coefficients will be under discussion. More precisely, the focus will lie on their connection with well known orthogonal polynomial sequences along with their foremost structural...



Nonsmooth atomic decompositions in function spaces and applications
20120330

Speaker: Cornelia Schneider (Univ. ErlangenNuremberg, Germany)

We provide nonsmooth atomic decompositions for Besov spaces \Bd(\rn), s>0, 0<p,q\leq \infty, defined via differences, with the help of a homogeneity property.The results are used to compute the trace of Besov spaces on the boundary \Gamma of bounded Lipschitz domains \Omega with smoothness s...



Counting spectral radii of matrices with positive entries
20120321

Speaker: Pedro Freitas (CELC/Mat. FCUL)

We will present some results concerning the number of different spectral radii that you can get for matrices with entries in a prescribed finite set of positive integers. This problem is related to a conjecture by Erdös and Szemerédi about sums and products of elements in a finite set....



On Leibniz algebras and Loday algebroids
20120320

Speaker: Yvette KosmannSchwarzbach (École Polytechnique, France)

We shall briefly review Leibniz algebras and their cohomology. We shall then define Loday algebroids, give examples and outline their supergeometric interpretation, following the 2011 preprint by Grabowski, Khudaverdian and Poncin....



Hyperpolygons and moduli spaces of parabolic Higgs bundles
20120320

Speaker: Alessia Mandini (IST, Lisboa)

In this talk I will describe the geometry of the moduli space of polygons and of its hyperkaehler analogue, the so called hyperpolygon space. In particular I will discuss how these spaces are isomorphic to certain moduli spaces of stable, rank2, parabolic and parabolic Higgs (respectively) bundles....



Complementing comonads
20120320

Speaker: Craig Pastro (Kyushu University, Japan)

TBA...



Monoidal structures
20120320

Speaker: Dimitri Chikhladze (CMUC)

TBA...



Spectral properties of certain tridiagonal kToeplitz matrices
20120316

Speaker: Renato ÁlvarezNodarse (Univ. Sevilla, Spain)

Motivated by a physical model of a system of quantum oscillators with nonlinear interactions, we study spectral properties of certain matrices which arise as perturbations of some tridiagonal kToeplitz matrices. Concretely, we are interested in the spectral properties of general ...



On the enumeration of connected graphs with specified biconnected components
20120314

Speaker: Ângela Mestre (CELC)

We derive a recurrence for the number of connected graphs whose biconnected components are all graphs on the same vertex and edge numbers. The proof uses Abel's binomial theorem and generalizes Dziobek's induction proof of Cayley's formula....



Optimal partition problems involving Laplacian eigenvalues
20120309

Speaker: Hugo Tavares (CMAF, Univ. Lisboa)

Given a bounded domain \Omega\subseteq \RN, N\geq 2, and a positive integer m\in \N, consider the following optimal partition problem \inf{ \sum_{i=1}^m \lambdak(\omegai): \omegai \subset \Omega open \forall i, \omegai\cap \omegaj=\emptyset whenever i\neq j},where \lambdak(\omega) denotes the...



Semiskyline augmented fillings and a nonsymmetric Cauchy identity in type A
20120307

Speaker: Aram Emami (PhD student CMUC)

The well known Cauchy identity is the best characterization of Schur functions that can be derived using the RobinsonSchenstedKnuth (RSK) correspondence. The Cauchy kernel expands as a sum, over all partitions, of products of Schur functions in variables X and Y separately. The RSK algorithm...



Network Optimisation with nondeterministic arc parameters: an application to bloodstream object location
20120307

Speaker: Deolinda M. L. D. Rasteiro (ISEC)

Abstract: In this talk we propose algorithms which determine the path that minimizes the expected value of a utility function over a dynamic probabilistic network with discrete or continuous real random variables (parameters) associated to each emerging arc. To obtain the optimal dynamic path from...



Immanant preserving and immanant converting maps
20120229

Speaker: Maria Antónia Duffner Monteiro (CELC/Mat. FCUL)

Let Mn be the algebra of all nsquare complex matrices. I will characterize maps φ:Mn→Mn that satisfy: dχ(φ(A)+λφ(B)) = dχ'(A+λB) for all A,B ∈ Mn and every complex number λ; where χ and χ' are arbitrary irreducible complex...



Mal'tsev categories and a generalised 3x3 Lemma
20120228

Speaker: Diana Rodelo (CMUC/Univ. Algarve)

We prove that a regular category C is a Mal'tsev category if and only if a strong form of the denormalised 3x3 Lemma holds true in C....



Shreier Mac Lane theorem in the Mal'cev context
20120228

Speaker: Dominique Bourn (Univ. du Littoral, Calais, France)

TBA...



Enumerative results and poset structure for a class of binary matrices equipped with a generalization of the Bruhat order
20120222

Speaker: Alessandro Conflitti (CMUC)

Recently, Brualdi et al. defined a partial order on an interesting class of binary matrices which generalizes the classical Bruhat order on the symmetric group, seen as the set of permutation matrices. We study the structure of this poset, and we give some enumerative results, e.g. about the maximal...



Higher central extensions via binary commutators
20120220

Speaker: Tim Van der Linden (Univ. catholique de Louvain, Belgium)

We prove that all semiabelian categories with the Smith is Huq property satisfy the Commutator Condition: higher central extensions may be characterised in terms of binary (Huq or Smith) commutators. In fact, even binary Higgins commutators suffice. As a consequence, in presence of enough...



Semidirect products and split short five lemma in algebraic categories
20120220

Speaker: Andrea Montoli (CMUC)

N. Martins Ferreira and M. Sobral proved that, in a pointed regular category C, the split epimorphisms are equivalent to the internal actions if and only if C is protomodular and every internal action is strict. We will show that, even if C is not protomodular, the regular split epimorphisms (i.e....



Topological space objects via neighbourhood systems
20120220

Speaker: Nelson MartinsFerreira (IP Leiria/CDRSP)

In this talk we consider the problem of defining a topological space object internal to an arbitrary category (perhaps with some extra structure, or appropriate conditions) in such a way that a topological space object in the category SET, of sets and maps, is a topological space, while, for...



Quantization in complex analysis and operator theory
20120217

Speaker: Nelson Faustino (CMUC)

In this talk it will be explored the relevance of quantization on the construction of polyanalytic function spaces likewise its relevance on the study of class of Toeplitz operators obtained from Berezin quantization. Starting from a group representation for the Heisenberg group...



Ribbon Schur functions with full support and Schur positivity
20120215

Speaker: Olga Azenhas (CMUC/Univ. Coimbra)

It is known that the Schur expansion of a skew Schur function runs in a subposet of the dominance lattice with top element and bottom element. The support of a skew Schur function consists of the partitions indexing Schur functions which appear in the Schur expansion with a positive...



Tunnel number degeneration under the connected sum of prime knots
20120215

Speaker: João Nogueira (CMUC/Univ. Coimbra)

In this talk, a study on 2string free tangle decompositions of knots with tunnel number two will be presented. As an application, we construct infinitely many counterexamples to a conjecture in the literature stating that the tunnel number of the connected sum of prime knots doesn't degenerate by...



Geometry and Topology of 3cosymplectic manifolds
20120215

Speaker: Antonio de Nicola (CMUC)

In this talk, we deal with 3cosymplectic manifolds which are the closest odddimensional analogue of hyperKähler structures, just as cosymplectic manifolds are the closest odddimensional analogue of Kähler structures. After a brief introduction to the geometric properties of...



On the solution set of the matrix equation AXXA=I
20120201

Speaker: Eduardo Marques de Sá (CMUC)

Matrix equations like AXYB=C and AXXB=C have been extensively studied in the literature because of their importance in linear control. The case AXXA=I has also been considered, though briefly; as the commutator AXXA has zero trace, our equation has solutions only if the base field has finite...



Models and algorithms for network design problems
20120126

Speaker: Michael Poss (Univ. Libre de Bruxelles, Belgium)

In this talk, we will have a rapid look at diverse problems arising in the context of network design. We start with a brief introduction to enumeration techniques used in integer programming. Then, we present different problems occurring in telecommunications and electrical power systems. We study...



The minimum description length in line transect sampling
20120120

Speaker: Russell AlpizarJara (Univ. Évora)

Population density estimation in line transect sampling requires fitting a probability density function denoted by f(yѲ), where y represents the perpendicular distance from a detected animal (or object) to a transect line, and Ѳ represents the vector parameter indexing this family...



Global dissipative solutions of a coupled problem for image restoration
20120120

Speaker: Dmitry Vorotnikov (CMUC)

We consider a coupled nonlinear PDE model for image restoration. Both image and edge variables are incorporated by coupling them into two different PDEs. The features of our problem which oppose strong and classical weak wellposedness are the presence of a nonlinear function (modulus) of the image...



Wellfounded and wellpointed coalgebras
20120120

Speaker: Lurdes Sousa (IP Viseu/CMUC)

A coalgebra (A,a) of an endofunctor H is wellfounded if the square Hm.a'=a.m is not a pullback for any proper subcoalgebra m:(A',a')>(A,A). For a graph, seen as a coalgebra of the powerset functor, this is exactly the usual definition of wellfounded graph, as observed by G. Osius [O]. P....



Counting dominant regions in the mextended Catalan arrangement with a fixed separating wall
20120118

Speaker: Eleni Tzanaki (Univ. of Crete, Greece)

Athanasiadis introduced separating walls for a region in the mextended Catalan arrangement and used them to generalize the Narayana numbers. In this paper, we fix a hyperplane in the mextended Catalan arrangement for type A and calculate the number of dominant regions which have the fixed...



Geometry of MaurerCartan elements on complex manifolds
20120116

Speaker: Ping Xu (Penn State Univ., USA)

...



Compactifications of reductive groups as moduli stacks of bundles
20111214

Speaker: Johan Martens (Aarhus Univ., Denmark)

We will introduce a class of moduli problems for any reductive group G, whose moduli stacks provide us with (toroidal) equivariant compactifications of G. Morally speaking, the objects in the moduli problem could be thought of as stable maps of a twicepunctured sphere into the classifying stack...



Anomalous diffusion imaging through fractional order calculus
20111214

Speaker: Ercília Sousa (CMUC/Mat. FCTUC)

...



Applications of retinal imaging with photoreceptor resolution
20111214

Speaker: Sérgio Nascimento (Univ. Minho, Braga)

...



Integervalued bilinear time series models
20111129

Speaker: Isabel Pereira (Univ. Aveiro)

The analysis of count processes has become an important area of research in the last two decades. In this paper we consider the simple nonnegative integervalued bilinear process INBL(1,0,1,1). The parameter estimation is addressed and the problem of forecasting integervalued time series...



Characteristic free resolutions in Schur algebras
20111123

Speaker: Ana Paula Santana (CMUC/Mat. FCTUC)

Using the BorelSchur algebra, I construct explicit resolutions of Weyl modules for GL_n and of coSpecht modules. These resolutions provide an answer to the problem, posed in the 80's by A.Akin and D. A. Buchsbaum, of constructing finite explicit and universal resolutions of Weyl modules by direct...



A Selection of Insertiontype results Extending Katetov's procedure
20111123

Speaker: Javier Gutiérrez García (UPV, Bilbao, Spain)

TBA...



Normality vs. extremal disconnectedness: two sandwichtype results for the price of one
20111123

Speaker: Jorge Picado (Mat.FCTUC/CMUC)

Several results in the literature about normal and extremally disconnected spaces (like KatetovTong type theorems, Uryshon's type lemmas or Tietze's type lemmas) shape the idea that the two notions are somehow dual to each other and therefore can be studied in parallel.In this talk we will discuss...



New approaches to rational curves on general hypersurfaces
20111116

Speaker: Ethan Cotterill (CMUC)

Almost thirty years ago, Herb Clemens made a series of conjectures about rational curves on general projective hypersurfaces, the most famous of which predicts that every rational curve on a general quintic threefold is rigid, in the sense of deformation theory. In this talk we will discuss a proof...



Betti bounds for the StanleyReisner ring of a stellar subdivision
20111109

Speaker: Stavros Papadakis (CAMGSD, Lisboa)

The talk will be about recent joint work with Janko Boehm (Saarbruecken) which uses unprojection theory to give bounds for the betti numbers of the StanleyReisner ring of a stellar subdivision of a Gorenstein* simplicial complex. ...



Enumeration of Shi regions with a fixed separating wall
20111102

Speaker: Ricardo Mamede (CMUC/Mat. FCTUC)

In 2005 Athanasiadis generalized the Narayana numbers by introducing the concept of separating wall for a region in the extended Shi arrangement. Using this concept, Susanna Fishel, Eleni Tzanaki and Monica Vazirani were able to calculate the number of dominant regions which have a fixed hyperplane...



Geometric Invariant Theory for polarized curves
20111026

Speaker: Margarida Melo (CMUC/Mat FCTUC)

Geometric Invariant Theory (GIT) was introduced by Mumford and coauthors in order to deal with the problem of constructing quotients of algebraic varieties by the action of an algebraic group. It is particularly useful in the construction of moduli spaces within the category of algebraic...



Nonsmooth analysis and optimization
20111020

Speaker: Suvendu Ranjan Pattanaik (DMUC)

In this talk, we show that for a large class of optimization problems, the Lagrange multiplier rule can be derived from the socalled approximate multiplier rule and we prescribed an approximate gradient multiplier rule in handling nonsmooth problems. Also in this talk we will cover some of...



Tropical Teichmuller theory
20111012

Speaker: Filippo Viviani (CMUC/Roma Tre)

I will report on a joint work in progress with M. Chan and M. Melo in which we study a tropical analogous of the classical Teichmuller theory. In particular, we prove that the moduli space of pure tropical curves (constructed in a joint work with S. Brannetti and M. Melo) is the quotient of the...



Positivity, sums of squares and real algebraic varieties
20110928

Speaker: João Gouveia (Mat FCTUC)

In recent years, the theory of sums of squares emerged as a very useful tool for polynomial optimization. The development of approximation methods based on classic Positivstellensatzes, raised a number of interesting theoretical questions that relate to very classic subjects of algebraic geometry.In...



Lifts of convex sets
20110921

Speaker: João Gouveia (Mat FCTUC)

It is wellknown that some complicated polytopes can be represented as projections of much simpler polytopes permitting polynomial time algorithms for linear optimization over them. In 1991 Yannakakism established a connection between the existence of such lifts and the nonnegative rank of the slack...



Moment analysis of distributions: classical and recent results
20110920

Speaker: Jordan Stoyanov (Newcastle Univ., UK)

The main discussion will be on distributions and their characterization in terms of the moments. There are distributions which are unique (Mdeterminate) and others which are nonunique (Mindeterminate). When analyzing specific stochastic model we clarify why in some cases a distribution is...



Dualities in modal logics via the Kleisli construction
20110920

Speaker: Dirk Hofmann (U. Aveiro)

Motivated by questions in semantics of modal (propositional) logics, over the past years several duality results were established which extend the classical Priestley and Stone dualities. In this talk we will show how the Kleisli construction for monads can simplify their proof and presentation....



Estimating the adjustment coefficient in Risk Theory
20110916

Speaker: Ana Cristina Moreira de Freitas (Fac. Economia, Univ. Porto)

We consider the problem of estimating the adjustment coefficient R in the Sparre Andersen model, which allows us to estimate upper bounds for the ruin probability of insurance companies.We propose a consistent estimator for R and establish a result about its asymptotic normality. Moreover, we show...



Sets with small sumset and small periodic productset
20110914

Speaker: Cristina Caldeira (CMUC/Mat. FCTUC)

We characterize the pairs (A,B) of finite nonempty subsets of a field such that the productset, AB, is periodic and both the sumset, A+B, and the productset, AB, are as small as possible, that is, A+B=min{p, A+B1} and AB=max{A,B}, where p is the characteristic of the underlying field...



Veering triangulations admit strict angle structures
20110726

Speaker: Henry Segerman (University of Melbourne, Australia)

Agol recently introduced the concept of a veering taut triangulation of a 3manifold, which is a taut ideal triangulation with some extra combinatorial structure. Hodgson, Rubinstein, Tillmann and I show that each veering triangulation admits a strict angle structure, which is a necessary condition...



The subgroup restriction problem for the general linear group
20110720

Speaker: Emmanuel Briand (Univ. Sevilla, Spain)

Let H ⊂ G be reductive groups. Each irreducible representation of G is also a representation of H, but not necessarily irreducible. How does it decompose into irreducibles ? How to describe and compute the multiplicities in its decomposition ? This is the "subgroup restriction problem"...



Baire sets and the Boolean reflection of sigmaframes
20110630

Speaker: Bernhard Banaschewski (McMaster University, Canada)

For any topological space X, the σfield BX of its Baire sets is the Boolean subσalgebra of the power set of X generated by the σframe Coz X of the cozero sets of X. Apart from this, one obviously has the abstractly defined Boolean σframe reflection BCoz X and the...



On monotone normality and subfitness
20110630

Speaker: Javier Gutiérrez García (Univ. Basque Country, Bilbao, Spain)

The notion of monotone normality was introduced in 1973 by Heath, Lutzer and Zenor as a strengthening of normality and is probably what you would guess if asked to define "normal in a monotone way". Every metrizable space and every linearly ordered space is monotonically normal. In fact,...



Nonmeasurable cardinals and pointfree topology
20110628

Speaker: Bernhard Banaschewski (McMaster University, Canada)

The familiar classical results that(i) any extremally disconnected Pspace of nonmeasurable cardinal is discrete, and(ii) any discrete space of nonmeasurable cardinal is realcompactare shown to be consequences of much more general results concerning frames. The particular frames involved here are...



Injectivity and the fibrewise waybelow relation
20110628

Speaker: Maria Manuel Clementino (Mat.FCTUC/CMUC)

Using results of EscardóFlagg [1] and Hofmann [2], we characterize continuous maps which are injective with respect to special classes of embeddings. These characterizations are based on a fibrewise waybelow relation which generalizes the one used by Richter in his characterization of...



The weighted Stieltjes inequality and application
20110617

Speaker: Amiran Gogatishvili (Institute of Mathematics of the Czech Academy of Sciences, Czech Republic)

Let $1<p\leq q<\infty$. Inspired by some results concerning characterization of weighted Hardy type inequalities, where the equivalence of four scales of integral conditions was proved, we use related ideas to find some new equivalent scales of integral conditions related to the...



The degree and the half degree principle for symmetric polynomials
20110615

Speaker: Alexander Kovacec (Mat. FCTUC)

Vlad Timofte proved in 2001/2 that a symmetric real polynomial F of degree d in n variables is nonnegative on certain subsets of Rn if and only if it is so on the subset of points with at most max{_d/2_,2} distinct components. His proof used ordinary differential equations. Quite recently...



Projecções empíricas e cartas antigas
20110602

Speaker: Joaquim Alves Gaspar (Centro Interuniversitário de História das Ciências e da Tecnologia, FCUL)

O conceito de "projecção empírica" foi utilizado em 1977, pelo geógrafo americano Waldo Tobler, para designar as representações cartográficas construídas de modo a obter determinadas propriedades, através de técnicas...



A glimpse on vector invariant theory I. The characteristic zero approach (after Capelli and Weyl)
20110527

Speaker: Francesco Regonati (Università di Bologna)

The characteristic zero approach can be founded on the socalled Weyl's Theorem (H. Weyl, The Classical Groups, 1946) which essentially says that a system of generators for the algebra of (absolute) vector invariants for any subgroup G of GL(d) can be constructed by polarizing a system of generators...
 