Institution: | Institute of Mathematics, Wroclaw University, Pl. grunwaldzki 2/4, 50--384 Wroclaw, Poland Andrzej Jasinski ; Institute of Mathematics, Wroclaw University, Pl. grunwaldzki 2/4, 50--384 Wroclaw, Poland Anastasis Kamburelis ; Institute of Mathematics, Wroclaw University, Pl. grunwaldzki 2/4, 50--384 Wroclaw, Poland ; Institute of Mathematics, Wroclaw University, Pl. grunwaldzki 2/4, 50--384 Wroclaw, Poland |