“…The simplicity of C * red (F n ) was proved in [16], and Powers' method has been extended to various free products [1], [13], or C * -algebras of discrete groups [5], [9], [10]. The proofs use technical estimates inside B(l 2 (A, τ )), which "move towards 0" any element having trace 0, by using sums of inner automorphisms, i.e.…”