Mathematical Foundations of Computer Science 2001 : 26th International symposium, MFCS 2001, Mariánské Lázně, Czech Republic, August 27-31, 2001 : proceedings - Sgall, Jiří, 1965-; Pultr, Aleš, 1938-; Kolman, Petr, 1976- (Lecture notes in computer science ;, 2001)