(* Contribution to the Coq Library   V6.3 (July 1999)                    *)
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(*                 The Calculus of Inductive Constructions                  *)
(*                                                                          *)
(*                                Projet Coq                                *)
(*                                                                          *)
(*                     INRIA                        ENS-CNRS                *)
(*              Rocquencourt                        Lyon                    *)
(*                                                                          *)
(*                                Coq V5.10                                 *)
(*                              Nov 25th 1994                               *)
(*                                                                          *)
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(*                                  Zgcd.v                                  *)
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Require Export misc.
Require Export Zadd.
Require Export Zle.
Require Export Euclid.
Require Export Peano_dec.
Require Export Zrec.
Require Export Zmult.
Require Export Zdiv.
Unset Standard Proposition Elimination Names.

(* Specifications: *)
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Lemma gcd_unicity_apart_sign :
forall a b d1 d2 : Z,
is_gcd Z IdZ multZ OZ a b d1 ->
is_gcd Z IdZ multZ OZ a b d2 -> d2 = d1 \/ d2 = oppZ d1.