(* Proof of lem_fun_sig_dom                                                *)
Qed.
(* End of proof of lem_fun_sig_dom                                         *)

Lemma lem_fun_sig_img : forall f a b : E, fun_sig f a b -> inc (Img f) b.
intros; elim H; clear H; intros; elim H0; clear H0; intros; auto with zfc.