Preface Volume 44, Issue 1

AbstractThis volume contains the Proceedings of the Fourth Workshop on Coalgebraic Methods in Computer Science (CMCS 2001). The Workshop was held in Genova, Italy on April 6 and 7, 2001, as a satellite event of ETAPS 2001. The aim of the CMCS workshop series is to bring together researchers with a common interest in theory of coalgebras and its applications. Previous workshops have been organized in Lisbon (1998), Amsterdam (1999) and Berlin (2000). The proceedings appeared as ENTCS Vols. 11,19 and 33.During the last few years it is becoming increasingly clear that a great variety of state-based dynamical systems, like transition systems, automata, process calculi and class-based systems can be captured uniformly as coalgebras. The first three volumes together with the current volume demonstrate that theory of coalgebras and its applications are developing into a field of its own interest presenting a deep mathematical foundation, a growing field of applications and interactions with various other fields, such as reactive and interactive system theory, object oriented and concurrent programming, formal system specification, modal logic, dynamical systems, control systems, category theory, algebra, analysis, etc.The Program Committee of CMCS 2001 consisted of Alexandru Baltag(Department of Software Technology, CWI)Andrea Corradini(Department of Computer Science, University of Pisa)Bart Jacobs(Department of Computer Science, University of Nijmegen)Marina Lenisa(Department of Mathematics and Computer Science, University of Udine)Ugo Montanari(Department of Computer Science, University of Pisa)Larry Moss(Department of Mathematics, Indiana University, Bloomington)Ataru T. Nakagawa(Software Research Associates, Tokyo)Dusko Pavlovic(Kestrel Institute, Palo Alto)John Power(Laboratory for Foundations of Computer Science, University of Edinburgh)Horst Reichel(Institute of Theoretical Computer Science, Dresden University of Technology)Jan Rutten(Department of Software Technology, CWI)The Invited Speakers of CMCS 2001 were Robin Cockett (University of Calgary) and Gordon Plotkin (University of Edinburgh).The papers in this volume were reviewed by the program committee members and by Falk Bartels, Anna Bucalo, Corina Cirstea, Pietro Di Gianantonio, Marcelo Fiore, Jesse Hughes, Alexander Kurz, Anna Labella, Lambert Meertens, Marino Miculan, Marco Pistore, Grigore Rosu, Doug Smith.This volume will be published in the series Electronic Notes in Theoretical Computer Science (ENTCS). This series is published electronically through the facilities of Elsevier Science B.V. and its auspices. The volumes in the ENTCS series can be accessed at the URL http://www.elsevier.nl/locate/entcsA printed version of the current volume is distributed to the participants at the workshop in Genova.We are very grateful to the following persons, whose help has been crucial for the success of CMCS 2001: Maura Cerioli and Gianna Reggio for their help with the organization of the Workshop as satellite event of ETAPS 2001; and Mike Mislove, Managing Editor of the ENTCS series, for his assistance with the use of the ENTCS style files. Thanks are also due to the Department of Computer Science of the University of Pisa, which has covered the printing cost of the copies distributed in Genova.Andrea Corradini, Marina Lenisa, Ugo MontanariMarch 13, 200