proposition: Lemma fold_Empty : forall m i, Empty m -> eqA (fold f m i) i.
proof: Proof. intros. apply fold_rec_nodep with (P:=fun a => eqA a i). - reflexivity. - intros. elim (H k e); auto. Qed.
imports: Bool DecidableType DecidableTypeEx OrderedType Morphisms FMapInterface