Please note that the list below only shows forthcoming events, which may not include regular events that have not yet been entered for the forthcoming term. Please see the past events page for a list of all seminar series that the department has on offer.

 

Past events in this series


Tue, 20 May 2025
14:00
L6

Dehn functions of Bestvina--Brady groups

Matteo Migliorini
(Karlsruhe Institute of Technology)
Abstract

Bestvina--Brady groups were first introduced by Bestvina and Brady for their interesting finiteness properties. In this talk, we discuss their Dehn functions, that are a notion of isoperimetric inequality for finitely presented groups and can be thought of as a "quantitative version" of finite presentability. A result of Dison shows that the Dehn function of a Bestvina--Brady group is always bounded above by a quartic polynomial.

Our main result is to compute the Dehn function for all finitely presented Bestvina--Brady groups. In particular, we show that the Dehn function of a Bestvina--Brady group grows as a polynomial of integer degree, and we present the combinatorial criteria on the graph that determine whether the Dehn functions of the associated Bestvina--Brady group is linear, quadratic, cubic, or quartic.

This is joint work with Chang and García-Mejía.

Tue, 20 May 2025
15:00
L6

Cohomology of subgroups of SL2

Henrique Souza
(Universidad Autonoma de Madrid)
Abstract

Given an FP-infinity subgroup G of SL(2,C), we are interested in the asymptotic behavior of the cohomology of G with coefficients in an irreducible complex representation V of SL(2,C). We prove that, as the dimension of V grows, the dimensions of these cohomology groups approximate the L2-Betti numbers of G. We make no further assumptions on G, extending a previous result of W. Fu. This yields a new method to compute those Betti numbers for finitely generated hyperbolic 3-manifold groups. We will give a brief idea of the proof, whose main tool is a completion of the universal enveloping algebra of the p-adic Lie algebra sl(2, Zp).

Tue, 27 May 2025
14:00
L6

TBC

Jon Pridham
(Edinburgh University)
Abstract

to follow

Tue, 03 Jun 2025
14:00
L5

tbc

Giovanna Carnoval
(University of Padova)
Abstract

to follow

Tue, 17 Jun 2025
14:00
L6

tbc

Finn Wiersig
(National University of Singapore)
Abstract

to follow