[1] Fern univ Hagen, Fac Math & Comp Sci, D-58097 Hagen, Germany
[2] Qingdao Univ Sci & Technol, Sch Data Sci, 99 Songling Rd, Qingdao 266061, Peoples R China
[3] Minnan Normal Univ, Sch Math & Stat, Zhangzhou, Peoples R China
[4] Beijing Jiaotong Univ, Sch Syst Sci, 3 Shangyuan Village, Beijing 100028, Peoples R China