proposition: Lemma conjsMg A B x : (A * B) :^ x = A :^ x * B :^ x.
proof: Proof. by rewrite !conjsgE !mulgA rcosetK. Qed.
imports: HB(structures) mathcomp(ssreflect ssrbool ssrfun eqtype ssrnat seq choice) mathcomp(fintype div path tuple bigop prime finset)