proposition: Lemma im_cpair_cprod : CH \* CK = C.
proof: Proof. by rewrite cprodE ?im_cpair. 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)