Analys- och sannolikhetsseminarium

Abstrakt finns enbart på engelska: We use an operator system approach to give new proofs of Wasserman's result that the full C*-algebras of free groups are non-exact and of Rosenberg's result that the reduced group C*-algebras of non-amenable groups are not quasi-diagonal. This approach also gives distance estimates between certain matrix convex sets and their various relaxations. Based on joint work with K. Davidson and M. Rahaman.