Centre for Mathematics, University of Coimbra

Seminars

On the protomodular and Mal'tsev properties for varieties of ordered algebras

2026-04-28

Speaker: Diana Rodelo (Univ. do Algarve)

The aim of the talk is to study the notions of lax protomodular category [1] and \( \mathsf{Ord} \)-Mal'tsev category [2] in the context of (coherent) varieties of (pre)ordered algebras and to compare them, as has been done in the non-ordered context. We characterise varieties of ordered...

Approximate addition for unital categories

2026-04-28

Speaker: Manuel Kahala Ostrogadsky (Univ. Agostinho Neto, Angola)

A variety is called Jónsson-Tarski if its algebraic theory contains a unique constant and a binary operation \( + \) satisfying \( x + 0 = 0 + x = x \).It is well known that this is equivalent to requiring the pair of morphisms \( \langle 1_X , 0\rangle\colon X \to X \times Y \) and \(...

Deformations of Lie algebroid morphisms and geometric structures

2026-04-29

Speaker: Sebastián Daza (CMUC, UC|UP PhD student)

In this talk we will see how to associate to a geometric structure a Lie algebroid morphism. Moreover, we will study deformations of Lie algebroid morphisms and define a deformation complex controlling such deformations. To conclude, we will apply this abstract formalism to study...

Unitriangular groups, pattern subgroups, and hypertopes

2026-04-29

Speaker: João Dias (Univ. de Évora)

We introduce pattern geometries, a new class of coset geometries constructed from pattern groups inside unitriangular groups \( U_n(q) \). Using a coset geometry framework, we define these geometries via families of maximal parabolic subgroups derived from the covering relations of an...

Nerves of T-categories and powerful T-functors

2026-05-04

Speaker: Soichiro Fujii (Kyoto Univ., Japan)

Burroni's \( T \)-categories generalize internal categories, which themselves generalize ordinary (small) categories. The classical nerve construction assigns to a small category a simplicial set, and this construction extends routinely to internal categories: any internal category in a...

Coinductive reasoning for parametrized functors and monads

2026-05-04

Speaker: Zeinab Galal (Kyoto Univ., Japan

Lax extensions (also called relators or relation liftings) are a categorical notion for reasoning about functors acting on functions and relations in a compatible way. They play a central role in developing sound proof principles for behavioral equivalence of state-based systems and are also...

Can a non-trivial isometric quotient of the unit n-sphere be made arbitrarily small?

2026-05-07

Speaker: Claudio Gorodski (Univ. São Paulo, Brazil)

We will explain our proof of the existence of \( \varepsilon >0 \) such that every quotient of the unit sphere \( S^n (n\geq 2) \) by a isometric group action has diameter zero or at least \( \varepsilon \). The novelty is the independence of \( \varepsilon \) from \( n \). The...

Multiscale problems on irregular domains with virtual element discretizations

2026-05-12

Speaker: Juan Gabriel Calvo (Univ. of Costa Rica, Costa Rica)

In this talk, we present an efficient approach for solving multiscale PDEs with high-contrast coefficients, combining multiscale ideas with domain decomposition techniques on irregular subdomains. The method is based on the Virtual Element Method and uses generalized multiscale constructions...

TBA

2026-06-16

Speaker: Rafael Díaz Fuentes (Università di Cagliari, Italy)

TBA...

TBA

2026-06-19

Speaker: Irene Fonseca (Carnegie Mellon University, USA)

TBA...

Using symplectic groupoid multiplication for Poisson integrators

2026-06-24

Speaker: Alejandro Cabrera (Uni. Politècnica de Catalunya, Spain)

TBA...

TBA

2026-09-28

Speaker: Peter Gothen (Univ. of Porto)

TBA...

Universality and special functions

2026-10-22

Speaker: Thomas Kriecherbauer (Univ. of Bayreuth, Germany)

Universality is the somewhat surprising observation that the behavior of quite different models, sometimes even stemming from different branches of mathematics or physics, may be described by the same class of special functions. An example for this phenomenon that has attracted a good deal...

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