auto.
Qed.
Definition l_egal (l1 l2 : wordset) : Prop :=
l_inclus l1 l2 /\ l_inclus l2 l1.
Hint Unfold l_egal.
(*predicat equivalent a eqwordset*)
(*demonstration :                *)

Lemma equiv_l_egal_eqwordset :
forall a b : wordset, l_egal a b <-> eqwordset a b.