Non-<i>K</i>-exact uniform Roe C*-algebras
Non-<i>K</i>-exact uniform Roe C*-algebras
Abstract We prove that uniform Roe C*-algebras C * u X associated to some expander graphs X coming from discrete groups with property (τ) are not K -exact. In particular, we show that this is the case for the expander obtained as Cayley graphs of a sequence of alternating groups …