Groups and Operator Algebras Seminar

Speaker: Pieter Spaas

Title: On compact extensions of W*-dynamical systems

Abstract: During this talk, we are interested in group actions on tracial von Neumann algebras. We start with providing some equivalent characterizations of compact extensions in this setting, and use them to generalize several classical results from ergodic theory. We will indicate some of the difficulties one encounters when trying to generalize classical Furstenberg-Zimmer theory, and then provide some positive results, as well as counterexamples obstructing a completely analogous generalization. This is based on joint work with Asgar Jamneshan.