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