Groups and Dynamics Seminar

Date: October 29, 2014

Time: 3:00PM - 4:00PM

Location: BLOC 220

Speaker: Yair Hartman, Weizmann Institute

Title: The Furstenberg entropy realization problem

Abstract: Stationary actions are a generalization of measure preserving actions, in the context of a random walk on a group. The Furstenberg entropy of a stationary action is an important invariant which measures its "distance from invariance". The realization problem is to determine the possible entropy values realizable for a given random walk. In this talk we will see a new characterization of Kazhdan's property (T) in terms of this problem (for non-singular actions) and will use Invariant Random Subgroups (IRSs) in order to describe a full solution of the problem for lamplighter groups. Based of several joint works with Lewis Bowen, Omer Tamuz and Ariel Yadin