proposition: Lemma Disjoint_Empty_set_left: forall {A} (P: Ensemble A), Disjoint A (Empty_set A) P.
proof: Proof. intros. apply Included_Complement_Disjoint. apply Constructive_sets.Included_Empty. Qed.
imports: Coq.Classes.Morphisms Coq.Classes.Equivalence Coq.Sets.Ensembles Coq.Sets.Constructive_sets CertiGraph.lib.Coqlib CertiGraph.lib.EquivDec_ext