November 6th 2017;  15:00;  Seminar room C3b/158
Joachim Zacharias, On weak and strong exactness of locally compact groups

Abstract:  Exactness is an important approximation property for C*-algebras, related to nuclearity but much weaker. For locally compact groups there are two natural notions of exactness: a weak one which says that the reduced group algebra is an exact C*-algebra and a strong one which asserts that given any exact sequence of dynamical systems over the group the corresponding sequence of reduced crossed products is exact. Strong implies weak exactness and for discrete groups it is known that the two concepts are equivalent but in the general locally compact case this is still open. We discuss background and indicate how the general locally compact case can be reduced to the totally disconnected case.
(Joint work with Chris Cave)