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, 03 Dec 2024
16:00
C3

The space of traces of certain discrete groups

Raz Slutsky
(University of Oxford)
Abstract

A trace on a group is a positive-definite conjugation-invariant function on it. These traces correspond to tracial states on the group's maximal  C*-algebra. In the past couple of decades, the study of traces has led to exciting connections to the rigidity, stability, and dynamics of groups. In this talk, I will explain these connections and focus on the topological structure of the space of traces of some groups. We will see the different behaviours of these spaces for free groups vs. higher-rank lattices, and how our strategy for the free group can be used to answer a question of Musat and Rørdam regarding free products of matrix algebras. This is based on joint works with Arie Levit, Joav Orovitz, and Itamar Vigdorovich.

Thu, 05 Dec 2024
16:00
C3

C*-diagonals in the C*-algebras of non-principal twisted groupoids

Anna Duwenig
(KU Leuven)
Abstract

The reduced twisted C*-algebra A of an étale groupoid G has a canonical abelian subalgebra D: functions on G's unit space. When G has no non-trivial abelian subgroupoids (i.e., G is principal), then D is in fact maximal abelian. Remarkable work by Kumjian shows that the tuple (A,D) allows us to reconstruct the underlying groupoid G and its twist uniquely; this uses that D is not only masa but even what is called a C*-diagonal. In this talk, I show that twisted C*-algebras of non-principal groupoids can also have such C*-diagonal subalgebras, arising from non-trivial abelian subgroupoids, and I will discuss the reconstructed principal twisted groupoid of Kumjian for such pairs of algebras.

Tue, 21 Jan 2025
16:00
C3

TBC

Kan Kitamura
(Riken iThems)
Abstract

to follow

Tue, 28 Jan 2025
16:00
C3

TBC

Nivedita Nivedita
((University of Oxford))
Abstract

to follow

Tue, 11 Feb 2025
16:00
C3

TBC

Alistair Miller
(University of Southern Denmark)
Abstract

to follow

Tue, 18 Feb 2025
16:00
C3

TBC

Stefaan Vaes
(KU Leuven)
Abstract

to follow

Tue, 25 Feb 2025
16:00
C3

TBC

Valerio Bianchi
(Cardiff University)
Abstract

to follow

Tue, 04 Mar 2025
16:00
C3

TBC

Adriana Fernández I Quero
(University of Iowa)
Abstract

to follow

Tue, 11 Mar 2025
16:00
C3

TBC

Safoura Zadeh
(University of Bristol )
Abstract

to follow