We reformulate the Baum–Connes conjecture with coefficients by introducing a new crossed product
functor for
-algebras.
All confirming examples for the original Baum–Connes conjecture remain confirming
examples for the reformulated conjecture, and at present there are no known
counterexamples to the reformulated conjecture. Moreover, some of the known
expander-based counterexamples to the original Baum–Connes conjecture become
confirming examples for our reformulated conjecture.