Affiliation: | 1. School of Computer Science, Hunan University of Science & Technology, Xiangtan 411201, China;Department of Mathematics, Southwest Normal University, Chongqing 400715, China;Department of Mathematics, Soochow University, Suzhou 215000, China 2. Department of Mathematics, Southwest Normal University, Chongqing 400715, China 3. Faculty of Science, The Chinese University of Hong Kong, Shatin, N. T., Hong Kong, China |