2013-08-16: actually use the hash-table to check the union.

actually use the hash-table to check the union.

diff --git a/unicode-math-fun.w b/unicode-math-fun.w
old mode 100644
new mode 100755
--- a/unicode-math-fun.w
+++ b/unicode-math-fun.w
@@ -19,7 +19,7 @@ define : ∩ list1 list2
             if : equal? tocheck '()
                 . inboth
                 let : : cur : list-ref tocheck 0
-                    if : member cur list2
+                    if : hash-ref h cur
                         loop 
                             append inboth : list cur
                             list-tail tocheck 1