exists (singleton zero).
exists zero.
exists (singleton zero).
exists (prodcart empty (prodcart alph empty)).
split.
red in |- *; auto.
red in |- *; split.
red in |- *.
symmetry  in |- *; apply lwordnil_is_reg2.
assumption.
intro.
compute in H.
rewrite <- H.
apply lwordnil_is_reg1.
Qed.
(*  D'ou bien sur...							*)

(* Specifications: *)
Lemma lwordnil_is_reg : isregular (lword nil).
cut
(exists q : Ensf,
(exists e : Elt,
(exists qa : Ensf,
(exists d : Ensf,
automate q (singleton e) qa d /\
eqwordset (reconnait q (singleton e) qa d) (lword nil))))).