diff --git a/src/fr/inrialpes/exmo/align/impl/edoal/Linkkey.java b/src/fr/inrialpes/exmo/align/impl/edoal/Linkkey.java
index 2fe0842ff7744d1c108b3b8616fff098096ee4ec..f0358ae3581dec0568f5138dc584911425703d14 100644
--- a/src/fr/inrialpes/exmo/align/impl/edoal/Linkkey.java
+++ b/src/fr/inrialpes/exmo/align/impl/edoal/Linkkey.java
@@ -1,7 +1,7 @@
 /*
- * $Id: BasicCell.java 1878 2014-01-29 14:52:55Z euzenat $
+ * $Id$
  *
- * Copyright (C) INRIA, 2003-2005, 2007-2010
+ * Copyright (C) INRIA, 2015
  *
  * This program is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public License
@@ -82,4 +82,14 @@ public class Linkkey implements Extensible {
 	    return (String)null;
 	}
     };
+
+    public Linkkey inverse() {
+	Linkkey lk = new Linkkey();
+	for ( LinkkeyBinding bind : bindings ) {
+	    lk.addBinding( bind.inverse() );
+	}
+	if ( extensions != null ) lk.setExtensions( extensions );
+	return lk;
+    };
+
 }
diff --git a/src/fr/inrialpes/exmo/align/impl/edoal/LinkkeyBinding.java b/src/fr/inrialpes/exmo/align/impl/edoal/LinkkeyBinding.java
index 8ecb9d093afbf07123da95181a910f236df5c753..bb85d697846f23fe288e607a19bd6af18cc99e72 100644
--- a/src/fr/inrialpes/exmo/align/impl/edoal/LinkkeyBinding.java
+++ b/src/fr/inrialpes/exmo/align/impl/edoal/LinkkeyBinding.java
@@ -1,7 +1,22 @@
 /*
- * To change this license header, choose License Headers in Project Properties.
- * To change this template file, choose Tools | Templates
- * and open the template in the editor.
+ * $Id$
+ *
+ * Copyright (C) INRIA, 2015
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public License
+ * as published by the Free Software Foundation; either version 2.1 of
+ * the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
+ * USA.
  */
 
 package fr.inrialpes.exmo.align.impl.edoal;
@@ -14,12 +29,12 @@ import org.semanticweb.owl.align.AlignmentException;
  */
 public abstract class LinkkeyBinding {
     
-    private PathExpression expression1;
-    private PathExpression expression2;
+    protected PathExpression expression1;
+    protected PathExpression expression2;
     
-    public LinkkeyBinding(PathExpression expression1, PathExpression expression2) throws AlignmentException {
-        this.expression1 = expression1;
-        this.expression2 = expression2;
+    public LinkkeyBinding( PathExpression expr1, PathExpression expr2 ) {
+        expression1 = expr1;
+        expression2 = expr2;
     }
    
     
@@ -32,4 +47,5 @@ public abstract class LinkkeyBinding {
     
     public abstract void accept( EDOALVisitor visitor ) throws AlignmentException;
     
+    public abstract LinkkeyBinding inverse();
 }
diff --git a/src/fr/inrialpes/exmo/align/impl/edoal/LinkkeyEquals.java b/src/fr/inrialpes/exmo/align/impl/edoal/LinkkeyEquals.java
index c52ed8bae85f5df3e62d7b20f973730e0f42ea11..759edf9262323f5caa8752277f3cb1df4ccb666d 100644
--- a/src/fr/inrialpes/exmo/align/impl/edoal/LinkkeyEquals.java
+++ b/src/fr/inrialpes/exmo/align/impl/edoal/LinkkeyEquals.java
@@ -1,7 +1,22 @@
 /*
- * To change this license header, choose License Headers in Project Properties.
- * To change this template file, choose Tools | Templates
- * and open the template in the editor.
+ * $Id$
+ *
+ * Copyright (C) INRIA, 2015
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public License
+ * as published by the Free Software Foundation; either version 2.1 of
+ * the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
+ * USA.
  */
 
 package fr.inrialpes.exmo.align.impl.edoal;
@@ -14,11 +29,15 @@ import org.semanticweb.owl.align.AlignmentException;
  */
 public class LinkkeyEquals extends LinkkeyBinding{
     
-    public LinkkeyEquals(PathExpression expression1, PathExpression expression2) throws AlignmentException {
-        super(expression1, expression2);
+    public LinkkeyEquals( PathExpression expression1, PathExpression expression2 ) {
+        super( expression1, expression2 );
     }
     
     public void accept( EDOALVisitor visitor ) throws AlignmentException {
 	visitor.visit( this );
     }
+
+    public LinkkeyEquals inverse() {
+	return new LinkkeyEquals( expression1, expression2 );
+    }
 }
diff --git a/src/fr/inrialpes/exmo/align/impl/edoal/LinkkeyIntersects.java b/src/fr/inrialpes/exmo/align/impl/edoal/LinkkeyIntersects.java
index 13fc58fbdda065b6e56ddd3d99099dba0d211290..be47e0864f076b18cbb552f5d7601f639d0a0d4e 100644
--- a/src/fr/inrialpes/exmo/align/impl/edoal/LinkkeyIntersects.java
+++ b/src/fr/inrialpes/exmo/align/impl/edoal/LinkkeyIntersects.java
@@ -1,7 +1,22 @@
 /*
- * To change this license header, choose License Headers in Project Properties.
- * To change this template file, choose Tools | Templates
- * and open the template in the editor.
+ * $Id$
+ *
+ * Copyright (C) INRIA, 2015
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public License
+ * as published by the Free Software Foundation; either version 2.1 of
+ * the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
+ * USA.
  */
 
 package fr.inrialpes.exmo.align.impl.edoal;
@@ -12,13 +27,18 @@ import org.semanticweb.owl.align.AlignmentException;
  *
  * @author Nicolas Guillouet <nicolas@meaningengines.com>
  */
-public class LinkkeyIntersects  extends LinkkeyBinding{
+
+public class LinkkeyIntersects extends LinkkeyBinding {
     
-    public LinkkeyIntersects(PathExpression expression1, PathExpression expression2) throws AlignmentException {
-        super(expression1, expression2);
+    public LinkkeyIntersects( PathExpression expression1, PathExpression expression2 ) {
+        super( expression1, expression2 );
     }
     
     public void accept( EDOALVisitor visitor ) throws AlignmentException {
 	visitor.visit( this );
     }
+
+    public LinkkeyIntersects inverse() {
+	return new LinkkeyIntersects( expression1, expression2 );
+    }
 }