proposition: Lemma mem_class_support A x : x \in A -> x \in class_support A G.
proof: Proof. by move=> Ax; rewrite -[x]conjg1 memJ_class_support. Qed.
imports: HB(structures) mathcomp(ssreflect ssrbool ssrfun eqtype ssrnat seq choice) mathcomp(fintype div path tuple bigop prime finset)