This volume contains the invited papers and papers selected for presentation at the 25th conference on Theory and Practice of Informatics | SOFSEM '98, held in Jasn a, Slovakia, November 21{27, 1998. The SOFSEM conference series started in 1974 as a local event in Czec- slovakia and from the very beginning became the top domestic event in software theory and practice. It has been unique in several respects, being a mix of w- ter school, conference, and advanced workshop. It brought together professionals from academia and industry and provided an opportunity for both theoreti- ans and practitioners to learn about the new developments in a broad range of computer science subjects via a series of invited talks. The conference gradually evolved into an international event, keeping most of its original characteristics. It features a relatively large number of invited talks, refereed papers (contributed papers), and refereed poster contributions. In addition, time and space for ?ash communications, industrial presentations, and exhibitions are provided. SOFSEM is every year result of a considerable e ort by a number of p- ple.Its Advisory Board (Dines Bj rner, Manfred Broy, Michal Chytil, Peter van Emde Boas, Georg Gottlob, Keith G. Je rey, Maria Zemankova) and - dowment Board (Keith G. Je rey, Jan Pavelka, Franti sek Pl a sil, Igor Pr vara, Branislav Rovan, vice-chair, Jan Staudek, Ji r Wiedermann, chair) is in process of being transformed into a Steering Committee.
