Affiliation: | 1. Department of Mathematics, East China Normal University, Shanghai 200062, China;2. Laboratoire de Recherche en Informatique, UMR 8623, C.N.R.S.-Université de Paris-sud, 91405-Orsay cedex, France;3. Department of Mathematics, Taizhzou University, Linhai Zhejiang 317000, China |