1. Department of Computer Engineering and Mathematics, Universitat Rovira i Virgili, Tarragona, Spain
2. Hellenic Open University, Patras, Greece
3. Norwegian University of Science and Technology (NTNU), Gjøvik, Norway
4. Aalborg University, Copenhagen, Denmark
5. CONFIRM Centre, University of Limerick, Limerick, Ireland
6. Vrije Universiteit Brussel, Brussels, Belgium
7. Department of Mathematics, University of Padua, Padua, Italy
8. Athena Research Center, Information Management Systems Institute, Marousi, Greece