Am. Sinclair et Rr. Smith, THE COMPLETELY BOUNDED APPROXIMATION PROPERTY FOR DISCRETE CROSSED-PRODUCTS, Indiana University mathematics journal, 46(4), 1997, pp. 1311-1322
We consider the relationship between the Haagerup constants for a C-a
lgebra and its crossed product by an amenable group. We prove equality
when the group is discrete, and deduce equality when the group is com
pact and abelian.