X-Git-Url: http://git.megacz.com/?p=sbp.git;a=blobdiff_plain;f=src%2Fedu%2Fberkeley%2Fsbp%2FUnion.java;h=db0db7dca1a322625895ee88f6d338a7934623ba;hp=a7a76302455b8e9c051224abd3fe022a2a828bb8;hb=242a8711e98cbd3ed6d05271bf910fde38e9be9a;hpb=87f214f3da9f43c3ab93923313845c372f9a96be

diff --git a/src/edu/berkeley/sbp/Union.java b/src/edu/berkeley/sbp/Union.java
index a7a7630..db0db7d 100644
--- a/src/edu/berkeley/sbp/Union.java
+++ b/src/edu/berkeley/sbp/Union.java
@@ -23,10 +23,10 @@ public class Union extends Element implements Iterable<Sequence> {
         Topology ret = null;
         for(Sequence s : this) {
             Topology a = s.toAtom();
-            if (a==null) continue;
             if (ret==null) ret = a.dup();
-            else           ret.add(a.dup());
+            else           ret = ret.union(a.dup());
         }
+        if (ret==null) throw new RuntimeException("confusion on " + this);
         return ret;
     }