diff -r fb4fe9f8c3cd -r d64593bb95d3 Arith.thy
--- a/Arith.thy	Wed May 25 12:43:50 1994 +0200
+++ b/Arith.thy	Wed May 25 13:03:19 1994 +0200
@@ -15,8 +15,8 @@
   div,mod  :: "[nat,nat]=>nat"	(infixl 70)
 rules
   pred_def  "pred(m) == nat_rec(m, 0, %n r.n)"
-  add_def   "m+n == nat_rec(m, n, %u v.Suc(v))"  
-  diff_def  "m-n == nat_rec(n, m, %u v. nat_rec(v, 0, %x y.x))"  
+  add_def   "m+n == nat_rec(m, n, %u v. Suc(v))"  
+  diff_def  "m-n == nat_rec(n, m, %u v. pred(v))"  
   mult_def  "m*n == nat_rec(m, 0, %u v. n + v)"  
   mod_def   "m mod n == wfrec(trancl(pred_nat), m, %j f. if(j<n, j, f(j-n)))"  
   div_def   "m div n == wfrec(trancl(pred_nat), m, %j f. if(j<n, 0, Suc(f(j-n))))"