1. University of Jyväskylä; P.O.Box 35 40014 Finland
2. St. Petersburg Department of V.A. Steklov Mathematical Institute; 191011, Fontanka 27 and Peter the Great St. Petersburg Polytechnic University; 195251 Politekhnicheskaya 29 St. Petersburg Russia
3. Institute of Mathematics and Biomathematics; Faculty of Science; University of South Bohemia; Branišovská 31; 37005 České Budějovice Czech Republic
4. The Czech Academy of Sciences; Institute of Information Theory and Automation; Pod vodárenskou věží 4 18208 Praha 8 Czech Republic