[1] Beijing Normal Univ, Sch Math Sci, Lab Math & Complex Syst, Beijing 100875, Peoples R China
[2] Univ Bretagne Sud, CNRS, LMBA, UMR 6205, Campus Tohannic, F-56000 Vannes, France
[3] Changsha Univ Sci & Technol, Sch Math & Stat, Changsha 410004, Hunan, Peoples R China