proposition: Lemma conjsgE A x : A :^ x = x^-1 *: (A :* x).
proof: Proof. by apply/setP=> y; rewrite mem_lcoset mem_rcoset -mulgA mem_conjg. Qed.
imports: HB(structures) mathcomp(ssreflect ssrbool ssrfun eqtype ssrnat seq choice) mathcomp(fintype div path tuple bigop prime finset)