proposition: Lemma prodfV I r (P : pred I) (E : I -> F) : \prod_(i <- r | P i) (E i)^-1 = (\prod_(i <- r | P i) E i)^-1.
proof: Proof. by rewrite (big_morph _ invfM (invr1 F)). Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat div seq) mathcomp(choice fintype finfun bigop prime binomial)