## Dynamics, Geometry, & Groups Seminar

### Thursday, February 4th, 2021

**Time:** 1:30 p.m** Place:**

**Speaker:** Nir Lazarovich (Technion Israel Institute of Technology)

**Title:** Flexible Stability of Surface Groups.

**Abstract:** Roughly speaking, a finitely presented group is said to be (flexibly) stable if any approximate action of the group on a finite set is an approximation of an action. Stability is closely related to local testability (in CS), soficity of groups, and residual finiteness. In this joint work with Arie Levit and Yair Minsky, we show that surface groups are flexibly stable using the geometry of CAT(-1) spaces and a new quantitative variant of LERF.