proposition: Lemma rpred_prod I r (P : pred I) F : (forall i, P i -> F i \in S) -> \prod_(i <- r | P i) F i \in S.
proof: Proof. by move=> IH; elim/big_ind: _; [apply: rpred1 | apply: rpredM |]. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat div seq) mathcomp(choice fintype finfun bigop prime binomial)