Affiliation: | (1) Department of Information and Communication Systems Engineering, University of the Aegean, GR 832 00 Karlovasi Samos, Greece;(2) Department of Informatics, Hellenic Open University, Patras, Greece;(3) Department of Mathematics, University of the Aegean, GR 832 00 Karlovasi Samos, Greece;(4) Department of Informatics, Athens University of Economics and Business, 76 Patission street, GR 104 34 Athens, pGreece |