Kazhdan projections, random walks and ergodic theorems

Piotr Nowak  (Institute of Mathematics of the Polish Academy of Sciences; University of Warsaw)

10:40 am to 11:40 am, May 12th, 2015    Science Building A1510


A Kazhdan projection is a central idempotent in the maximal group C*-algebra, whose image under any unitary representation is the projection onto the subspace of invariant vectors. I will present a new construction of Kazhdan projection via random walks that is very flexible and allows to construct such projections in the setting of uniformly convex spaces. I will also present several applications, including a definition of property tau for uniformly convex Banach spaces, comparison with Lafforgue’s strong Banach property (T), and a construction of new examples of non-compact ghost projections, which answers a question of Willet and Yu.

This is joint work with Cornelia Drutu.

About the speaker:

Piotr Nowak is an assistant professor at Institute of Mathematics of the Polish Academy of Sciences and University of Warsaw