[Ding, Xingjian;Wang, Yongcai;Luo, Chuanwen;Li, Deying;Chen, Wenping] Renmin Univ China, Sch Informat, Beijing 100872, Peoples R China.^[Sun, Guodong] Beijing Forestry Univ, Sch Informat, Beijing 100083, Peoples R China.^[Hu, Qian] Cent China Normal Univ, Sch Math & Stat, Wuhan 430079, Peoples R China.