intros a b.
unfold iff in |- *.
split.
intro Hyp; elim Hyp; auto.
intros Hyp.
split; unfold l_inclus in |- *; intro w; elim (Hyp w); auto.
Qed.

Lemma refl_l_egal : forall l1 : wordset, l_egal l1 l1.
auto.