nat_arith_tac -> arith_tac

--- a/src/HOLCF/IOA/NTP/Impl.ML	Thu Jan 14 13:18:09 1999 +0100
+++ b/src/HOLCF/IOA/NTP/Impl.ML	Thu Jan 14 13:19:12 1999 +0100
@@ -178,14 +178,14 @@
   by (forward_tac [rewrite_rule [Impl.inv1_def]
                                 (inv1 RS invariantE) RS conjunct1] 1);
   by (tac2 1);
-  by(nat_arith_tac 1);
+  by(arith_tac 1);
 
   (* 3 *)
   by (forward_tac [rewrite_rule [Impl.inv1_def] (inv1 RS invariantE)] 1);
 
   by (tac2 1);
   by (fold_tac [rewrite_rule [Packet.hdr_def]Impl.hdr_sum_def]);
-  by(nat_arith_tac 1);
+  by(arith_tac 1);
 
   (* 2 *)
   by (tac2 1);