proposition: Lemma big_mkcondl I r (P Q : pred I) F : \big[*%M/1]_(i <- r | P i && Q i) F i = \big[*%M/1]_(i <- r | Q i) (if P i then F i else 1).
proof: Proof. by rewrite big_andbC big_mkcondr. Qed.
imports: HB(structures) mathcomp(ssreflect ssrbool ssrfun eqtype ssrnat seq path) mathcomp(div fintype tuple finfun)