Affiliation: | (1) Department of Computer Science, Southwest Normal University, Chongqing, 400715, People's Republic of China;(2) Dipartimento di Matematica e Informatica, Universita di Udine, via delle Scienze 208, I-33100 Udine, Italy;(3) Institute of Mathematics, Southwest Normal University, Chongqing, 400715, People's Republic of China |