1. Guangxi Key Laboratory of Universities Optimization Control and Engineering Calculation, and College of Sciences Guangxi University for Nationalities Nanning Guangxi 530006 P.R. China
2. Institute of Mathematics Lodz University of Technology ul. Wolczanska 215 Lodz 90924 Poland
3. College of Sciences Beibu Gulf University Qinzhou Guangxi 535000 P.R. China
4. Faculty of Mathematics and Computer Science Jagiellonian University in Krakow ul. Łojasiewicza 6 Krakow 30348 Poland