1. Department of Informatics, University of Huddersfield, Huddersfield, UK
2. Department of Computer Science, Czech Technical University in Prague, Prague, Prague Czech Republic
3. Department of Theoretical Computer Science and Mathematical Logic, Charles University in Prague, Prague, Prague Czech Republic
4. Dipartimento d’Ingegneria dell’Informazione, Universitá degli Studi di Brescia, Brescia, Italy