X-Git-Url: http://matita.cs.unibo.it/gitweb/?a=blobdiff_plain;f=helm%2Fsoftware%2Fmatita%2Flibrary%2Fnat%2Fnat.ma;h=5e3e769ec11cf8778db2aa4d43986c5544b23d7e;hb=5c10d402b5de7233bc83d7f685b274832e383212;hp=9fce4df76a8b3dfbd7071582202ea648676d884b;hpb=2a31f145f58f7ba66b6445a9c8b31841054ef809;p=helm.git

diff --git a/helm/software/matita/library/nat/nat.ma b/helm/software/matita/library/nat/nat.ma
index 9fce4df76..5e3e769ec 100644
--- a/helm/software/matita/library/nat/nat.ma
+++ b/helm/software/matita/library/nat/nat.ma
@@ -1,5 +1,5 @@
 (**************************************************************************)
-(*       ___	                                                              *)
+(*       ___	                                                          *)
 (*      ||M||                                                             *)
 (*      ||A||       A project by Andrea Asperti                           *)
 (*      ||T||                                                             *)
@@ -18,6 +18,9 @@ inductive nat : Set \def
   | O : nat
   | S : nat \to nat.
 
+interpretation "Natural numbers" 'N = nat.
+alias num (instance 0) = "natural number".
+
 definition pred: nat \to nat \def
  \lambda n:nat. match n with
  [ O \Rightarrow  O