(* This code is copyrighted by its authors; it is distributed under  *)
(* the terms of the LGPL license (see LICENSE and description files) *)
(* Contribution to the Coq Library   V6.3 (July 1999)                    *)
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(*                                                                          *)
(*                   Solange Coupet-Grimal & Line Jakubiec                  *)
(*                                                                          *)
(*                                                                          *)
(*              Laboratoire d'Informatique de Marseille                     *)
(*               CMI-Technopole de Chateau-Gombert                          *)
(*                   39, Rue F. Joliot Curie                                *)
(*                   13453 MARSEILLE Cedex 13                               *)
(*           e-mail:{Solange.Coupet,Line.Jakubiec}@lim.univ-mrs.fr          *)
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(*                                Coq V5.10                                 *)
(*                              May 30th 1996                               *)
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(*                              Lib_Zerob.v                                 *)
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Require Export Lib_Bool.
Require Export Lib_Prop.
Require Export Lib_Set_Products.
Require Export Lt.
simple induction b; simpl in |- *; intros; auto.
absurd (x <> 0).
apply no_no_A; apply zerob_true_elim; auto.
trivial.
Qed.
simple induction n; [ intros; inversion H | auto ].
Qed.
Hint Resolve lt_no_zerob.
simple induction n; auto with bool.
Qed.
Hint Resolve zerob_pred_no.
simple induction n.
simpl in |- *; intro.
absurd (true = false); auto with bool.
intros.
auto with arith.
Qed.
Hint Resolve zerob_lt.
simple induction n; auto.
Qed.
Hint Resolve no_zerob_true.

Lemma x_1_or_y_0 :
forall x y : nat,
zerob (pred x) || zerob y = true -> x <> 0 -> x = 1 \/ y = 0.