Institution: | 1.Department of Mathematics, Harbin University of Science and Technology, Harbin, 150080, China ;2.Faculty of Economics and Information Technology, The State University of Applied Sciences in P?ock, Nowe Trzepowo 55, 09-402 , P?ock, Poland ;3.Faculty of Mathematics and Computer Science, Adam Mickiewicz University in Poznań, Umultowska 87, 61-614, Poznań, Poland ;4.Faculty of Mathematics and Computer Science, Adam Mickiewicz University in Poznań, Umultowska 87, 61-614, Poznań, Poland ;5.Institute of Mathematics, Faculty of Electrical Engineering, Poznań University of Technology, Piotrowo 3A, 60-965, Poznań, Poland ; |