proposition: Lemma Frobenius_reg_compl : semiregular H K.
proof: Proof. by apply: semiregular_sym; apply: Frobenius_reg_ker. Qed.
imports: mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat div) mathcomp(fintype bigop prime finset fingroup morphism) mathcomp(perm action quotient gproduct cyclic center) mathcomp(pgroup nilpotent sylow hall abelian)