Speaker: Nathanial P. Brown (Pennsylvania State University)

Title: New C*-completions of groups and related spaces

Abstract: Given a group G, there are two common C*-completions of the group algebra: the reduced and full. But there are many other canonical completions determined by "rates of decay" of matrix coefficients. In joint work with Erik Guentner we've started to study these other completions and the results look promising. So far, we've found the first C*-characterization of a-T-menability, given new examples of "exotic" quantum groups, and substantially simplified and generalized a recent theorem of Ron Douglas and Piotr Nowak.