Affiliation: | Department of Mathematics and Statistics, University of Calgary, Canada;Computer Science Institute of Charles University (IUUK), Charles University, Czech Republic;Western Michigan University, Kalamazoo, Michigan 49008, USA;Theoretische Informatik, Universität Trier, Germany;Department of Computer Science, Comenius University, 842 48 Bratislava, Slovakia;Department of Computer Science, Comenius University, 842 48 Bratislava, Slovakia |