Group actions with spectral gap on surfaces

Venue:
20.30 SR 2.058

Date:
19.01.2023
 Speaker:

Time:
15:45

Spectral gap is an important rigidity property for group actions with various applications. One of these applications is the construction of families of expander graphs. I will explain a new class of actions with spectral gap on surfaces of arbitrary genus. These are the first examples of actions with spectral gap on surfaces of genus g > 1. I will also explain some of the surprising largescale geometric features of the expander families constructed from these actions. This is joint work with Goulnara Arzhantseva, Dawid Kielak, and Damian Sawicki.