[1] Shantou Univ, Dept Math, Shantou 515063, Guangdong, Peoples R China
[2] AGH Univ Sci & Technol, Fac Appl Math, Al Mickiewicza 30, PL-30059 Krakow, Poland
[3] Univ Ostrava, IT4Innovat, Natl Supercomp Ctr, Inst Res & Applicat Fuzzy Modeling, 30 Dubna 22, Ostrava 70103, Czech Republic