proposition: Lemma big_rmcond I (r : seq I) (P : pred I) F : (forall i, ~~ P i -> F i = 1) -> \big[*%M/1]_(i <- r | P i) F i = \big[*%M/1]_(i <- r) F i.
proof: Proof. move=> F_eq1; rewrite big_mkcond; apply: eq_bigr => i. by case: (P i) (F_eq1 i) => // ->. Qed.
imports: HB(structures) mathcomp(ssreflect ssrbool ssrfun eqtype ssrnat seq path) mathcomp(div fintype tuple finfun)