proposition: Lemma Same_set_refl: forall A (S : Ensemble A), Same_set S S.
proof: Proof. intros; split; intro; tauto. Qed.
imports: Coq.Classes.Morphisms Coq.Classes.Equivalence Coq.Sets.Ensembles Coq.Sets.Constructive_sets CertiGraph.lib.Coqlib CertiGraph.lib.EquivDec_ext