X-Git-Url: http://matita.cs.unibo.it/gitweb/?a=blobdiff_plain;f=matita%2Fmatita%2Fcontribs%2Flambdadelta%2Fground%2Farith%2Fnat_pred.ma;h=3d665506579765b2246ce3985a9458ed9154f49e;hb=68e028d053806177e218ee1a5f8778d3011bef83;hp=7c5d8a5ac5b6cf93c890880fafd4d6e28816dc7d;hpb=74c6905907b0bca229366d52450e2a6982b5b8be;p=helm.git

diff --git a/matita/matita/contribs/lambdadelta/ground/arith/nat_pred.ma b/matita/matita/contribs/lambdadelta/ground/arith/nat_pred.ma
index 7c5d8a5ac..3d6655065 100644
--- a/matita/matita/contribs/lambdadelta/ground/arith/nat_pred.ma
+++ b/matita/matita/contribs/lambdadelta/ground/arith/nat_pred.ma
@@ -16,7 +16,7 @@ include "ground/notation/functions/downarrow_1.ma".
 include "ground/arith/pnat_dis.ma".
 include "ground/arith/nat.ma".
 
-(* NON-NEGATIVE INTEGERS ****************************************************)
+(* PREDECESSOR FOR NON-NEGATIVE INTEGERS ************************************)
 
 (*** pred *)
 definition npred (m): nat ≝ match m with
@@ -25,10 +25,11 @@ definition npred (m): nat ≝ match m with
 ].
 
 interpretation
-  "predecessor (non-negative integers"
+  "predecessor (non-negative integers)"
   'DownArrow m = (npred m).
 
 (* Basic rewrites ***********************************************************)
 
+(*** pred_O *)
 lemma npred_zero: 𝟎 = ↓𝟎.
 // qed.