1. Department of Intelligent Computer Systems , Czestochowa University of Technology , Czestochowa , Poland
2. Management Department , University of Social Science , 90–113 Lodz , Poland
3. Clark University , Worcester, MA 01610, USA
4. Faculty of Computer Science and Telecommunications , Cracow University of Technology Warszawska 24, 31-155 Krakow , Poland
5. Department of Computer Science , Meiji University , Kawasaki 214-8571 Japan