proposition: Lemma uniq_mmaxP U : reflect (exists M, 'M(U) = [set M]) (U \in 'U).
proof: Proof. by rewrite inE; apply: cards1P. 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)