Linear Analysis Seminar

Date: February 23, 2017

Time: 3:00PM - 4:00PM

Location: BLOC 220

Speaker: Nicolas Matte Bon, ETH Zürich

Title: Chabauty dynamics and C*-simplicity of groups of homeomorphisms

Abstract: Let G be a countable group. The space of subgroups of G, endowed with the Chabauty topology, is naturally a compact space on which G acts continuously by conjugation. The talk will focus on the topological dynamics of this action, in particular on the study of its minimal invariant subsets (named uniformly recurrent subgroups). I will explain a method to study the uniformly recurrent subgroups of a class of groups of homeomorphisms, such as Thompson's groups and their relatives, some groups acting on rooted and non-rooted trees, topological full groups. I will discuss applications to the simplicity of the reduced C^*-algebra of these groups, linked to uniformly recurrent subgroups by results of Kennedy and Kalantar-Kennedy, and to rigidity-type results for non-free actions. This is a joint work with Adreian Le Boudec.