VU University Amsterdam, The Netherlands;Fondazione Bruno Kessler (FBK) - IRST Center for Information Technology, Trento, Italy 38100;University of Sheffield, United Kingdom;TU Delft, The Netherlands;Talis Information Ltd., United Kingdom;Semantic Computing Research Group (SeCo), Helsinki University of Technology, and University of Helsinki,, Finland;The Institute of Scientific and Industrial Research, Osaka University, Osaka, Japan 567-0047;VU University Amsterdam, The Netherlands;Knowledge Media Institute, The Open University, UK;STI Innsbruck, University of Innsbruck, Innsbruck, Austria 6020