proposition: Lemma cprodWpp A B G : A \* B = G -> pprod A B = G.
proof: Proof. by case/cprodP=> [[K H -> ->] <- /cents_norm/pprodE]. Qed.
imports: HB(structures) mathcomp(ssreflect ssrbool ssrfun eqtype ssrnat seq div) mathcomp(choice fintype bigop finset fingroup morphism) mathcomp(quotient action)