proposition: Lemma bigdprodWcp I (r : seq I) P F G : \big[dprod/1]_(i <- r | P i) F i = G -> \big[cprod/1]_(i <- r | P i) F i = G.
proof: Proof. elim/big_rec2: _ G => // i A B _ IH G /dprodP[[K H -> defB] <- cKH _]. by rewrite (IH H) // cprodE -defB. Qed.
imports: HB(structures) mathcomp(ssreflect ssrbool ssrfun eqtype ssrnat seq div) mathcomp(choice fintype bigop finset fingroup morphism) mathcomp(quotient action)