proposition: Lemma big_pred0 : forall r (P : pred I) F, P =1 xpred0 -> \big[op/idx]_(i <- r | P i) F i === idx.
proof: Proof. move=> r P F; move/eq_bigl=> Heq; rewrite -> Heq; exact: big_pred0_eq. Qed.
imports: ssreflect ssrbool ssrfun eqtype ssrnat seq div choice fintype finfun paths Setoid Morphisms OperationClasses bigops