Automata, Languages and Programming 28th International Colloquium, ICALP 2001 Crete, Greece, July 8-12, 2001 Proceedings - Orejas, Fernando; Orejas, Fernando; Spirakis, Paul G.; Spirakis, Paul G.; Leeuwen, Jan van; Leeuwen, Jan van (Springer Berlin Heidelberg : Imprint: Springer, 2001)