Affiliation: | 1. School of Mathematical Sciences and Wu Wen-Tsun Key Laboratory of Mathematics, University of Science and Technology of China, Hefei, Anhui 230026, China;2. Department of Mathematics, Harbin Institute of Technology in Weihai, Weihai, Shandong 264209, China;3. Department of Mathematics and Statistics, Memorial University of Newfoundland, St. John''s, NL A1C 5S7, Canada |