proposition: Lemma conjIg A B x : (A :&: B) :^ x = A :^ x :&: B :^ x.
proof: Proof. by rewrite !conjg_preim preimsetI. Qed.
imports: HB(structures) mathcomp(ssreflect ssrbool ssrfun eqtype ssrnat seq choice) mathcomp(fintype div path tuple bigop prime finset)