Preface Volume 39

AbstractA large class of systems can be specified and verified by abstracting away from the temporal aspects. This is the class of systems where time affects the performance but not the functional behaviour. In time-critical systems, instead, time issues become essential. Their correctness depends not only on which actions a system can perform but also on their execution time. Due to their importance, time-critical systems have attracted the attention of a considerable number of computer scientists from various research areas.This volume contains the Proceedings of the International Workshop on Models for Time-Critical Systems (MTCS 2000), held in State College (Pennsylvania, USA) 26 August 2000. The objectives of the workshop were (i) to validate the more promising proposals on models for time-critical systems and (ii) to promote interaction between different research areas in the field of time-critical systems.MTCS 2000 was one of the four satellite workshops of the 11th International Conference on Concurrency Theory (CONCUR 2000), held in State College (Pennsylvania, USA) 22-25 August 2000. The other three were: 7th International Workshop on Expressiveness in Concurrency (EXPRESS'00), 2nd Workshop on Geometric and Topological Methods in Concurrency Theory (GETCO 2000) and Why Object-Orientation (Y00).The six papers in this volume were selected by the Program Committee from submissions received in response to a Call for Papers. The final proceedings will appear as Volume 39 in the series Electronic Notes in Theoretical Computer Science (ENTCS). The volumes in the ENTCS series can be accessed at the URLhttp://www.elsevier.nl/locate/entcsWe would like to thank Catuscia Palamidessi and Dale Miller (CONCUR 2000 Conference Chairs) and Uwe Nestmann (Satellite Workshops Chair) for the opportunity they gave us to organize MTCS 2000 and for their continuous support. Many thanks are due to Thomas Henzinger (Invited Speaker) and to the members of the Program Committee as well as their sub-referees for their accurate work. We would also like to thank Michael Mislove for his help during the proceedings editorial process. Rajeev Alur(USA)Frank de Boer(NL)Flavio Corradini(IT)Roberto Gorrieri(IT)Paola Inverardi(IT)Amir Pnueli(IL)Bran Selic(CA)Joseph Sifakis(FR)Walter Vogler(DE