(* Proof of lem_vide_unicite                                               *)
generalize (lem_vide_propertie v2 v0); intros; elim H0; assumption.
generalize (lem_vide_propertie v2 v1); intros; elim H0; assumption.
Qed.
(* End of proof of lem_vide_unicite                                        *)
Parameter var_vide : E.
Definition Vide := vide var_vide.

Lemma lem_x_inc_vide : forall x : E, inc x Vide -> x = Vide.
intros.