proposition: Lemma big_pred0_eq : forall (r : seq I) F, \big[op/idx]_(i <- r | false) F i === idx.
proof: Proof. by move=> r F; rewrite -> (big_hasC)=> //; try apply H; try reflexivity; rewrite has_pred0. Qed.
imports: ssreflect ssrbool ssrfun eqtype ssrnat seq div choice fintype finfun paths Setoid Morphisms OperationClasses bigops