Affiliation: | 1. Institute of Mathematics, University of Bia?ystok, Akademicka 2, Pl 15267 Bia?ystok, Poland;2. Institute of Mathematics, University of Bia?ystok, Lipowa 41, Pl 15424 Bia?ystok, Poland;3. Institute of Physics, University of Silesia, Uniwersytecka 4, Pl 40007 Katowice, Poland |