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We say that a C*-algebra $A$ is K-exact, if for any exact sequence of C*-algebras

$0\rightarrow I\rightarrow B\rightarrow B/I\rightarrow0$, the sequences

$K_i(I\otimes_{min}A)\rightarrow K_i(B\otimes_{min}A)\rightarrow K_i(B/I\otimes_{min}A)$

are exact in the middle for both i=0,1.

Similarly, we can define a locally compact group $G$ to be K-exact, if for any exact sequence of G-C*-algebras

$0\rightarrow I\rightarrow B\rightarrow B/I\rightarrow0$, the sequences

$K_i(I\rtimes_r G)\rightarrow K_i(B\rtimes_r G)\rightarrow K_i(B/I\rtimes_r G)$

are exact in the middle for both i=0,1.

It is clear that $G$ is K-exact implies that $C^*_r(G)$ is K-exact C*-algebra.

My question is that is the converse implication also true for discrete groups.

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