[1] Inner Mongolia Univ, Sch Math Sci, 235 Daxuexilu Rd, Hohhot 010021, Inner Mongolia, Peoples R China
[2] Univ Nottingham, Sch Comp Sci, Nottingham NG8 1BB, England
[3] Univ Bretagne Sud, UMR 6205, Lab Math Bretagne Atlantique, Campus Tohannic,BP 573, F-56017 Vannes, France
[4] Nanjing Univ Informat Sci & Technol, Sch Comp & Software, Nanjing 210044, Peoples R China
[5] Shanghai Jiao Tong Univ, Inst Image Proc & Pattern Recognit, 800 Dongchuan Rd, Shanghai 200240, Peoples R China