Centre for Mathematics, University of Coimbra

Seminars

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

2025-05-22

Speaker: Pavel Etingof (MIT, Cambridge, USA)

We study the number of indecomposable summands in tensor powers of the vector representation of SL(2). Our main focus is on positive characteristic, where this sequence of numbers - and its generating function - exhibits fractal behavior reminiscent of Mahler functions. ...

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)

TBA...

Quandles, cohomology and quivers

2025-06-04

Speaker: Sam Nelson (Claremont McKenna College, USA)

Knot theorists seek knot invariants, tools we can use to distinguish knots from each other and to probe their structure. In this talk I will introduce quandles, an algebraic category whose axioms encode the motion of knots through space analogously to how the group axioms encode geometric...

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2025-06-17

Speaker: Alfredo Costa (CMUC, Univ. Coimbra)

TBA...

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2025-06-17

Speaker: Célia Borlido (CMUC, Univ. Coimbra)

TBA...

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2025-06-24

Speaker: Semyon Yakubovich (Univ. Porto)

TBA...

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2025-06-25

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

TBA...

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...

Drazin inverses in (dagger) categories

2025-08-19

Speaker: Jean-Simon Pacaud Lemay (Macquarie Univ., Sydney, Australia)

Drazin inverses are a special kind of generalized inverse that have been extensively studied and have many applications in ring theory, semigroup theory, and matrix theory. Drazin inverses can also be defined for endomorphisms in any category. A natural question is whether one can extend the...

A general approach to pointfree \(T_0\) spaces

2025-08-19

Speaker: Anna Laura Suarez (Univ. Western Cape, South Africa)

The classical dual adjunction between frames and spaces, given by the functors \( O\colon \mathbf{Top}\to\mathbf{Frm} \) and \( \mathsf{pt}\colon\mathbf{Frm}\to\mathbf{Top} \), restricts to a dual equivalence between sober spaces and spatial frames. Another pointfree approach to the study of...

Large random tilings of a hexagon

2025-09-15

Speaker: Arno Kuijlaars (KU Leuven, Belgium)

TBA...

Quasi-orthogonal polynomials and positive quadrature on the unit circle

2025-09-18

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

TBA...