unfold abit in |- *. exact (length_elemlist bool).
Qed.
(****************************************************************)
(* Defintitions des variables et leurs contraintes *)
Parameter size : nat. (* La taille des mots *)
Parameter V1 : BV. (* Les deux entrees *)
Parameter V2 : BV.

(* Specifications: *)
Axiom size_not_O : size <> 0. Hint Resolve size_not_O.
Axiom length_V1_size : lengthbv V1 = size. Hint Resolve length_V1_size.
Axiom length_V2_size : lengthbv V2 = size. Hint Resolve length_V2_size.
Lemma le_SO_size : 1 <= size.
generalize size_not_O. elim size. intro. absurd (0 <> 0); unfold not in |- *; auto with arith.