fact: Definition in_cprod : gTH * gTK -> cprod_by := let: tt as k := cprod_by_key return _ -> locked_with k cprod_by_def in subg _ \o coset kerHK.
imports: mathcomp(ssreflect ssrbool ssrfun eqtype ssrnat seq div) mathcomp(fintype bigop finset fingroup morphism perm) mathcomp(automorphism quotient action gproduct gfunctor) mathcomp(cyclic)