Affiliation: | a College of Mathematics and Computer Science, Hunan Normal University, Changsha, 410076 Hunan, Chinab College of Mathematics and Computing Science, Changsha University of Science and Technology, Changsha, 410076 Hunan, Chinac School of Mathematical Sciences, Beijing Normal University, Laboratory of Mathematics and Complex Systems, 100875 Beijing, Chinad LMAM, Université de Bretagne Sud, Campus de Tohannic, BP 573, 56017 Vannes, Francee Université Européenne de Bretagne, France |