--- /home/rubey/axiom/mnt/linux/src/algebra/combfunc.spad	2004-06-09 10:53:44.000000000 +0000
+++ combfunc.spad	2004-06-12 17:57:50.000000000 +0000
@@ -230,10 +230,10 @@
              + opdsum [differentiate(f, x), d, y, g, h]
 
     ddprod l ==
-      prod(summand(l)::O, third(l)::O = fourth(l)::O, fourth(rest l)::O)
+      paren(prod(summand(l)::O, third(l)::O = fourth(l)::O, fourth(rest l)::O))
 
     ddsum l ==
-      sum(summand(l)::O, third(l)::O = fourth(l)::O, fourth(rest l)::O)
+      paren(sum(summand(l)::O, third(l)::O = fourth(l)::O, fourth(rest l)::O))
 
     product(x:F, s:SegmentBinding F) ==
       k := kernel(variable s)$K
