1. École Polytechnique Fédérale de Lausanne, PFL IC IIF LSIR, BC 159 (Bâtiment BC), Station 14, CH-1015 Lausanne, Switzerland. E-mail: alex.constantin@epfl.ch
2. Department of Computer Science and Engineering, University of Bologna, Mura Anteo Zamboni 7, 40127 Bologna (BO), Italy. E-mails: silvio.peroni@unibo.it, fabio.vitali@unibo.it
3. Semantic Technology Laboratory, Institute of Cognitive Sciences and Technologies, National Research Council, Via Nomentana 56, 00161 Rome (RM), Italy
4. School of Computer Science, University of Manchester, Kilburn Building, M13 9PL Manchester, United Kingdom. E-mail: steve.pettifer@manchester.ac.uk
5. Oxford e-Research Centre, University of Oxford, 7 Keble Road, OX1 3QG Oxford, United Kingdom. E-mail: david.shotton@oerc.ox.ac.uk