arithmetics for λδ

[helm.git] / matita / matita / contribs / lambdadelta / ground / arith / nat_pred.ma

diff --git a/matita/matita/contribs/lambdadelta/ground/arith/nat_pred.ma b/matita/matita/contribs/lambdadelta/ground/arith/nat_pred.ma
index 7c5d8a5ac5b6cf93c890880fafd4d6e28816dc7d..fb196e042ebea1a5bd415272a7cc0aafbb7d39f0 100644 (file)
--- 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 ***********************************************************)
+(* Basic constructions ******************************************************)
 
+(*** pred_O *)
 lemma npred_zero: 𝟎 = ↓𝟎.
 // qed.