## EVENT DETAILS AND ABSTRACT

**Algebra Seminar**
**Title:** The measurable Kesten theorem

**Speaker:** Miklos Abert

**Speaker Info:**

**Brief Description:**

**Special Note**:

**Abstract:**

Let Gamma be a finitely generated group and N be a normal subgroup. Kesten's theorem (essentially his thesis) says that a random walk of Gamma sees N with exponentially larger probability than it sees the identity, if and only if N is a non-amenable group.
It is easy to see that this theorem is false when one omits the normality condition. In the talk I will extend Kesten's result in the measurable setting and show what this implies on the geometry of Ramanujan graphs. This is joint work with Yair Glasner and Balint Virag.

**Date:** Wednesday, December 5, 2012

**Time:** 2:00pm

**Where:** Lunt 104

**Contact Person:** Nir Avni

**Contact email:** nir@math.northwester.edu

**Contact Phone:**

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