proposition: Lemma Same_set_spec: forall A P Q, Same_set P Q <-> (pointwise_relation A iff) P Q.
proof: Proof. intros. unfold Same_set, Included, In, pointwise_relation. firstorder. Qed.
imports: Coq.Classes.Morphisms Coq.Classes.Equivalence Coq.Sets.Ensembles Coq.Sets.Constructive_sets CertiGraph.lib.Coqlib CertiGraph.lib.EquivDec_ext