proposition: Lemma mmax_ofJ K x M : ((M :^ x)%G \in 'M(K :^ x)) = (M \in 'M(K)).
proof: Proof. by rewrite inE mmaxJ conjSg !inE. Qed.
imports: HB(structures) mathcomp.ssreflect.ssreflect mathcomp(ssrbool ssrfun eqtype ssrnat seq div choice fintype bigop) mathcomp(finset prime fingroup morphism automorphism action quotient) mathcomp(gfunctor cyclic pgroup center commutator gseries nilpotent) mathcomp(sylow abelian maximal hall) odd_order(BGsection1 BGsection6)