Affiliation: | a College of Mathematics and Systems Sciences, Xinjiang University, Urumqi 830046, China b Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, PO Box 71010, 30 West Strict, Xiao-Hong-Shan, Wuhan 430071, China c Laboratoire de Mathématiques, Université de Franche-Comté, 25030 Besançon Cedex, France d Graduate School, Chinese Academy of Sciences, Wuhan 430071, China |