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(* 02110-1301 USA                                                     *)
(** natZ. Some lemmas about inject_nat, absolu and the relation between Z and nat in general.  @author Olga Caprotti and Martijn Oostdijk @version $Revision$ *)

Lemma isnat_abs_inj :
forall (x : Z) (n : nat), (0 <= x)%Z -> n = Z.abs_nat x -> x = Z_of_nat n.