Centre for Mathematics, University of Coimbra

Seminars

World of pseudoline arrangements

2025-05-14

Speaker: Sandro Roch (Technische Univ. Berlin, Germany)

A pseudoline arrangement is a collection of unbounded curves in the plane that resemble non-parallel straight lines: each pair of curves intersects exactly once. Despite their simple definition, pseudoline arrangements are deeply connected to a wide range of combinatorial...

Maintenance modelling and inference in a Wiener degradation model considering different observation schemes

2025-05-16

Speaker: María Lúcia Bárcena (Univ. Extremadura, Spain)

Industrial systems normally present interrelated parts that influence the system performance. For instance, lighting systems composed of many LED lamps, which present a likely dependence because of their common usage. Maintenance actions are performed on these systems to mitigate the...

Normed categories

2025-05-20

Speaker: Walter Tholen (York Univ., Toronto, Canada)

In this talk we explore Lawvere's notion of normed category through the lens of easily understood small and large example categories. Cauchy convergence of sequences in such categories gets presented as a natural extension of familiar concepts taught in Calculus and Functional Analysis, but...

Self-dual aspects of semi-abelian categories

2025-05-20

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

The aim of this talk is to introduce di-exact categories [3], which are defined by a simple axiom system capturing self-dual aspects of the context of Janelidze-Márki-Tholen semi-abelian categories [2,1]. A Borceux-Bourn homological category [1] is Barr-exact if and only if it is di-exact....

Fractal behavior of tensor powers of the two-dimensional space in prime characteristic

2025-05-22

Speaker: Pavel Etingof (MIT, Cambridge, USA)

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Polynomials whose roots are the differences of the roots of a given polynomial

2025-06-03

Speaker: Manuel A. Facas Vicente/José Vitória (DMUC, Univ. Coimbra)

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2025-06-17

Speaker: Alfredo Costa (CMUC, Univ. Coimbra)

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2025-06-17

Speaker: Célia Borlido (CMUC, Univ. Coimbra)

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2025-06-24

Speaker: Semyon Yakubovich (Univ. Porto)

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2025-06-25

Speaker: Mateus Moreira de Melo (Univ. Fed. Espírito Santo, Brazil)

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Classifying cubic graphs avoiding spectral gap sets

2025-06-25

Speaker: Gordon Royle (Univ. Western Australia, Australia)

Spectral graph theory is the study of the relationship between the graphical properties of a graph and the spectral properties (i.e., eigenvalues and eigenvectors) of various matrices associated with that graph, most commonly the adjacency matrix. The spectrum of the...

Large random tilings of a hexagon

2025-09-15

Speaker: Arno Kuijlaars (KU Leuven, Belgium)

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Quasi-orthogonal polynomials and positive quadrature on the unit circle

2025-09-18

Speaker: Ruymán Cruz Barroso (University of La Laguna, Spain)

TBA...