proposition: Lemma injm_cpair1g : 'injm cpair1g.
proof: Proof. rewrite /cpair1g; case: restrmP => _ [_ -> _ _]. rewrite ker_comp ker_in_cprod; apply/subsetP=> y; rewrite !inE /= morph1 invg1. by case/and3P. Qed.
imports: mathcomp(ssreflect ssrbool ssrfun eqtype ssrnat seq div) mathcomp(fintype bigop finset fingroup morphism perm) mathcomp(automorphism quotient action gproduct gfunctor) mathcomp(cyclic)