diff --git a/src/fr/inrialpes/exmo/align/impl/BasicOntologyNetwork.java b/src/fr/inrialpes/exmo/align/impl/BasicOntologyNetwork.java
index c5686dd951a59411df7a27b21b07d4fb3a301454..6b1ff163e06ad756c533e935df0742f0831e3a88 100644
--- a/src/fr/inrialpes/exmo/align/impl/BasicOntologyNetwork.java
+++ b/src/fr/inrialpes/exmo/align/impl/BasicOntologyNetwork.java
@@ -97,6 +97,11 @@ public class BasicOntologyNetwork implements OntologyNetwork {
 	if (!ontologies.containsKey(onto)) return Collections.emptySet();
 	return ontologies.get( onto ).sourceAlignments;
     };
+    public void invert() throws AlignmentException {
+	for ( Alignment al : alignments ) {
+	    addAlignment( al.inverse() );
+	}
+    }
 
 }
 
diff --git a/src/org/semanticweb/owl/align/OntologyNetwork.java b/src/org/semanticweb/owl/align/OntologyNetwork.java
index 9f9caaa115691ed51376b69c2edb7287fcf20744..7c62620d3048c484e377d0316489ed5d8b37074c 100644
--- a/src/org/semanticweb/owl/align/OntologyNetwork.java
+++ b/src/org/semanticweb/owl/align/OntologyNetwork.java
@@ -47,6 +47,11 @@ public interface OntologyNetwork extends Cloneable {
     public Set<Alignment> getTargetingAlignments( URI onto );
     public Set<Alignment> getSourceAlignments( URI onto );
 
+    /**
+     * close reflexively the network.
+     * The network is modified.
+     */
+    public void invert() throws AlignmentException;
 }