proposition: Lemma conjGid : {in G, normalised G}.
proof: Proof. by move=> x Gx; apply/setP=> y; rewrite mem_conjg groupJr ?groupV. Qed.
imports: HB(structures) mathcomp(ssreflect ssrbool ssrfun eqtype ssrnat seq choice) mathcomp(fintype div path tuple bigop prime finset)