Affiliation: | 1. Computer Science Institute, Charles University, Malostranské nám. 25, 118 00 Praha 1, Czech Republic;2. Department of Applied Mathematics and Institute for Theoretical Computer Science, Charles University, Malostranské nám. 25, 118 00 Praha 1, Czech Republic;3. Institute of Theoretical Informatics, Karlsruhe Institute of Technology, Box 6980, D-76128 Karlsruhe, Germany |