proposition: Lemma second_isog : H / (K :&: H) \isog H / K.
proof: Proof. by rewrite setIC -{1 3}(ker_coset K); apply: first_isog_loc. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq div) mathcomp(choice fintype prime finset fingroup morphism) mathcomp(automorphism)