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(* 02110-1301 USA                                                     *)
(* Contribution to the Coq Library   V6.3 (July 1999)                    *)
(****************************************************************************)
(*                 The Calculus of Inductive Constructions                  *)
(*                                                                          *)
(*                                Projet Coq                                *)
(*                                                                          *)
(*                     INRIA                        ENS-CNRS                *)
(*              Rocquencourt                        Lyon                    *)
(*                                                                          *)
(*                                Coq V5.10                                 *)
(*                              Nov 25th 1994                               *)
(*                                                                          *)
(****************************************************************************)
(*                                 RatReg.v                                 *)
(****************************************************************************)
(*              Formal Language Theory                                      *)
(*                                                                          *)
(*              Judicael Courant - Jean-Christophe Filliatre                *)
(*                                                                          *)
(*              Developped in V5.8  June-July 1993                          *)
(*              Ported     to V5.10 October 1994                            *)
(****************************************************************************)
(************************************************************************)
(*									*)
(*            Un langage reduit a un mot est regulier.			*)
(*									*)
(************************************************************************)
(*  Le mot vide est reconnu par un automate reduit a un etat (zero)	*)
(*  et sans transition.							*)
unfold reconnait at 1 in |- *.
split.
apply inmonoid_nil.
exists zero; exists zero.
auto.
Qed.
(* Seul le mot vide est reconnu par l'automate ci-dessus.		*)

Lemma lwordnil_is_reg2 :
forall w : Word,
reconnait (singleton zero) (singleton zero) (singleton zero)
(prodcart empty (prodcart alph empty)) w -> w = nil :>Word.