proposition: Lemma image_Same_set: forall {A B: Type} (f: A -> B) (X Y: Ensemble A), Same_set X Y -> Same_set (image_set X f) (image_set Y f).
proof: Proof. intros. unfold Same_set in *. split; apply image_Included; tauto. Qed.
imports: Coq.Classes.Morphisms Coq.Classes.Equivalence Coq.Sets.Ensembles Coq.Sets.Constructive_sets CertiGraph.lib.Coqlib CertiGraph.lib.EquivDec_ext