Index: trunk/autoquest-core-usageprofiles/src/main/java/de/ugoe/cs/autoquest/usageprofiles/DefaultSymbolComparator.java
===================================================================
--- trunk/autoquest-core-usageprofiles/src/main/java/de/ugoe/cs/autoquest/usageprofiles/DefaultSymbolComparator.java	(revision 1189)
+++ trunk/autoquest-core-usageprofiles/src/main/java/de/ugoe/cs/autoquest/usageprofiles/DefaultSymbolComparator.java	(revision 1196)
@@ -26,4 +26,7 @@
 public class DefaultSymbolComparator<T> implements SymbolComparator<T> {
 
+    /**  */
+    private static final long serialVersionUID = 1L;
+
     /* (non-Javadoc)
      * @see de.ugoe.cs.autoquest.tasktrees.temporalrelation.SymbolComparator#equals(java.lang.Object, java.lang.Object)
Index: trunk/autoquest-core-usageprofiles/src/main/java/de/ugoe/cs/autoquest/usageprofiles/SymbolComparator.java
===================================================================
--- trunk/autoquest-core-usageprofiles/src/main/java/de/ugoe/cs/autoquest/usageprofiles/SymbolComparator.java	(revision 1189)
+++ trunk/autoquest-core-usageprofiles/src/main/java/de/ugoe/cs/autoquest/usageprofiles/SymbolComparator.java	(revision 1196)
@@ -15,4 +15,6 @@
 package de.ugoe.cs.autoquest.usageprofiles;
 
+import java.io.Serializable;
+
 /**
  * <p>
@@ -22,5 +24,5 @@
  * @author Patrick Harms
  */
-public interface SymbolComparator<T> {
+public interface SymbolComparator<T> extends Serializable {
     
     /**