proposition: Lemma image_Empty: forall {A B: Type} (f: A -> B), Same_set (image_set (Empty_set _) f) (Empty_set _).
proof: Proof. intros. rewrite Same_set_spec. intro x. rewrite image_set_spec. pose proof Noone_in_empty A. pose proof Noone_in_empty B. firstorder. Qed.
imports: Coq.Classes.Morphisms Coq.Classes.Equivalence Coq.Sets.Ensembles Coq.Sets.Constructive_sets CertiGraph.lib.Coqlib CertiGraph.lib.EquivDec_ext