Affiliation: | 1. Department of Information Engineering, Computer Science and Mathematics, University of L’Aquila, L’Aquila, Italy.marco.castellani@univaq.it;3. Department of Information Engineering, Computer Science and Mathematics, University of L’Aquila, L’Aquila, Italy.;4. Department of Mathematics, University of Isfahan, Isfahan, Iran.;5. Department of Computer Science, University of Pisa, Pisa, Italy. |