I am currently trying to understand the general Green-Julg theorem, where $G$ is a compact group, $A$ and $B$ are $G$-$C^*$-algebras, and where $G$ acts trivially on $A$. The Green-Julg theorem states that there is an isomorphism $$ \mathrm{KK}^G(A,B) \rightarrow \mathrm{KK}(A, B\rtimes G).$$ Unfortunately, in all of the papers I can find, it's always the special case $A=\mathbb{C}$. Does anybody know a good paper where a proof is given for the general case?

Thank you.

  • $\begingroup$ If true what you say, I think you can simply copy the usual Green-Julg proof and inherit the additional $\varphi:A\rightarrow L(E)$ of the Kasparov cycle $(\varphi,E)\in KK^G(A,B)$. Because $G$ acts trivially, $A \rtimes G = A \otimes G$ under the descent in the proof. $\endgroup$ – hänsel Mar 10 '18 at 12:05

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