Index: src/main/java/org/openrdf/query/algebra/helpers/QueryModelVisitorBase.java
===================================================================
--- src/main/java/org/openrdf/query/algebra/helpers/QueryModelVisitorBase.java	(Revision 7669)
+++ src/main/java/org/openrdf/query/algebra/helpers/QueryModelVisitorBase.java	(Arbeitskopie)
@@ -56,6 +56,7 @@
 import org.openrdf.query.algebra.QueryRoot;
 import org.openrdf.query.algebra.Regex;
 import org.openrdf.query.algebra.SameTerm;
+import org.openrdf.query.algebra.Set;
 import org.openrdf.query.algebra.SingletonSet;
 import org.openrdf.query.algebra.Slice;
 import org.openrdf.query.algebra.StatementPattern;
@@ -359,6 +360,12 @@
 		meetBinaryValueOperator(node);
 	}
 
+	public void meet(Set node)
+		throws X
+	{
+		meetNode(node);
+	}
+
 	public void meet(SingletonSet node)
 		throws X
 	{
Index: src/main/java/org/openrdf/query/algebra/Set.java
===================================================================
--- src/main/java/org/openrdf/query/algebra/Set.java	(Revision 0)
+++ src/main/java/org/openrdf/query/algebra/Set.java	(Revision 0)
@@ -0,0 +1,26 @@
+/*
+ * Copyright Aduna (http://www.aduna-software.com/) (c) 1997-2006.
+ *
+ * Licensed under the Aduna BSD-style license.
+ */
+package org.openrdf.query.algebra;
+
+
+/**
+ * A tuple expression that contains exactly one solution with zero bindings.
+ */
+public abstract class Set extends QueryModelNodeBase implements TupleExpr {
+
+	public abstract int cardinality();
+
+	public <X extends Exception> void visit(QueryModelVisitor<X> visitor)
+		throws X
+	{
+		visitor.meet(this);
+	}
+
+	@Override
+	public Set clone() {
+		return (Set)super.clone();
+	}
+}
Index: src/main/java/org/openrdf/query/algebra/QueryModelVisitor.java
===================================================================
--- src/main/java/org/openrdf/query/algebra/QueryModelVisitor.java	(Revision 7669)
+++ src/main/java/org/openrdf/query/algebra/QueryModelVisitor.java	(Arbeitskopie)
@@ -155,6 +155,9 @@
 	public void meet(Filter node)
 		throws X;
 
+	public void meet(Set node)
+ 		throws X;
+
 	public void meet(SingletonSet node)
 		throws X;
 
Index: pom.xml
===================================================================
--- pom.xml	(Revision 7669)
+++ pom.xml	(Arbeitskopie)
@@ -9,7 +9,7 @@
 	</parent>
 
 	<artifactId>sesame-queryalgebra-model</artifactId>
-	<version>2.2-SNAPSHOT</version>
+	<version>2.2-set-injection-SNAPSHOT</version>
 
 	<name>OpenRDF Sesame: Query algebra - model</name>
 	<description>A generic query algebra for RDF queries.</description>