proposition: Lemma Same_set_trans: forall A (S1 S2 S3: Ensemble A), Same_set S1 S2 -> Same_set S2 S3 -> Same_set S1 S3.
proof: Proof. intros; destruct H, H0; split; repeat intro; [apply H0, H, H3 | apply H1, H2, H3]. Qed.
imports: Coq.Classes.Morphisms Coq.Classes.Equivalence Coq.Sets.Ensembles Coq.Sets.Constructive_sets CertiGraph.lib.Coqlib CertiGraph.lib.EquivDec_ext