X-Git-Url: http://git.megacz.com/?p=sbp.git;a=blobdiff_plain;f=src%2Fedu%2Fberkeley%2Fsbp%2FUnion.java;h=1d4841ff718c4aaf272a0bf83902218605458fde;hp=7370a6834307c40a3e70dc98017120274475d071;hb=2f167f63aff4b6da4d82669faf2c7ada4c93be4b;hpb=93ea8e84f6eadb1b2549754bbb832c75e4730e86

diff --git a/src/edu/berkeley/sbp/Union.java b/src/edu/berkeley/sbp/Union.java
index 7370a68..1d4841f 100644
--- a/src/edu/berkeley/sbp/Union.java
+++ b/src/edu/berkeley/sbp/Union.java
@@ -36,6 +36,9 @@ public class Union extends Element implements Iterable<Sequence> {
         this.synthetic = synthetic;
     }
 
+    public static Union epsilon = new Union("()");
+    static { epsilon.add(Sequence.empty); }
+
     private Forest.Ref epsilonForm = null;
     Forest epsilonForm() {
         if (epsilonForm != null) return epsilonForm;