EURO courses 3 COMPUTER AND INFORMATION SCIENCE VOLUME 5 Distributed Artificial Intelligence: Theory and Praxis edited by Nicholas M. Avouris and Les Gasser "1 Kluwer Academic Publishers for the Commission of the European Communities Distributed Artificial Intelligence: Theory and Praxis EURO C O U R S ES A series devoted to the publication of courses and educational seminars organized by the Joint Research Centre Ispra, as part of its education and training program. Published for the Commission of the European Communities, Directorate- General Telecommunications, Information Industries and Innovation, Scientific and Technical Communications Service. The EUROCOURSES consist of the following subseries: - Advanced Scientific Techniques - Chemical and Environmental Science - Energy Systems and Technology - Environmental Impact Assessment - Health Physics and Radiation Protection - Computer and Information Science - Mechanical and Materials Science - Nuclear Science and Technology - Reliability and Risk Analysis - Remote Sensing - Technological Innovation COMPUTER AND INFORMATION SCIENCE Volume 5 The publisher will accept continuation orders for this series which may be cancelled at any time and which provide for automatic billing and shipping of each title in the series upon publication. Please write for details. Distributed Artificial Intelligence Theory and Praxis Edited by Nicholas M. Avouris Commission of the European Communities, Joint Research Centre, Institute for Systems Engineering and Informatics, Ispra, Italy and Les Gasser Institute of Safety and Systems Management, University of California, Los Angeles, CA, U.S.A. PARL EURCP. Biblioth. et¿t /MfH . .'. w. ri KLUWER ACADEMIC PUBLISHERS DORDRECHT / BOSTON / LONDON Based on the lectures given during the Eurocourse on Distributed Artificial Intelligence: Theory and Praxis held at the Joint Research Centre, Ispra, Italy, July 1-5,1991 ISBN 0-7923-1585-5 Publication arrangements by Commission of the European Communities Directorate-General Telecommunications, Information Industries and Innovation, Scientific and Technical Communication Unit, Luxembourg EUR 14511 © 1992 ECSC, EEC, EAEC, Brussels and Luxembourg LEGAL NOTICE Neither the Commission of the European Communities nor any person acting on behalf of the Commission is responsible for the use which might be made of the following information. Published, by Kluwer Academic Publishers, P.O. Box 17, 3300 AA Dordrecht, The Netherlands. Kluwer Academic Publishers incorporates the publishing programmes of D. Reidel, Martinus Nijhoff, Dr W. Junk and MTP Press. Sold and distributed in the U.S.A. and Canada by Kluwer Academic Publishers, 101 Philip Drive, Norwell, MA 02061, U.S.A. In all other countries, sold and distributed by Kluwer Academic Publishers Group, P.O. Box 322,3300 AH Dordrecht, The Netherlands. Printed on acid-free paper All Rights Reserved No part of the material protected by this copyright notice may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording or by any information storage and retrieval system, without written permission from the copyright owner. Printed in the Netherlands Preface The papers in this book are, for the most part, based on lectures, research presen tations, and discussions that took place during the 1991 Eurocourse on Distributed Artificial Intelligence, sponsored by the Eurocourses Secretariat of the Commission of the European Communities (CEC), and held at the CEC's Joint Research Center at Ispra, Italy. The course was attended by approximately 40 people from 13 different countries spanning the globe. This course was a broad-ranging scientific presentation aimed at transmitting core DAI knowledge and the practical experience of experienced developers, and on promoting discussion and real investigation of some key DAI re search issues. In keeping with the modular style of the Eurocourse, the book comprises a collection of individual contributions arranged so as to present a unified whole. Some authors reflect on their practice in DAI and DAI system design. Others present compendia of DAI theory or technology in digestible, tutorial form. Thus, each chapter in the book is intended to make a specific point and can be read for its own contributions. Simultaneously, it takes its place as a section of the book, augmenting an emerging picture of DAI as a growing enterprise of both research and practice. The production of the Eurocourse and of this book placed significant demands on the time and energy of many people. Their common commitment to DAI and to involving new people in the field has led to the present result. We are especially grateful to the other lecturers and authors who so willingly devoted their time and energy to planning and carrying out the Eurocourse and to preparing contributions for the book: Jean- Pierre Briot, Yves Demazeau, Alexis Drogoul, Jacques Ferber, Lynne Hall, Georgios Lekkas, Greg O'Hare, Nick Jennings, Michael Roboam, Jeff Rosenschein, Katia Sycara, Marc Van Liedekerke, Theis Wittig, and M.J. Wooldridge. In addition, we appreciate the kind and forbearing encouragement of Kluwer's Nel De Boer. We are happy to acknowledge the staff at JRC Eurocourses and especially Mr. Giovanni Pellegrini, who gracefully and expertly handled any contingencies that arose during the DAI week. The Commission for the European Communities, DG XIII, Esprit deserves credit for supporting the course financially. We also would like to thank Dr. Flavio Argentesi, head of the Knowledge-Based Systems Laboratory of Joint Research Center, and the JRC staff for providing logistic and other support for the course organization. We are also, of course, grateful to the Eurocourse attendees, who helped make the DAI week a stimulating and enjoyable one for all. We thank the members of the LAFORIA Laboratory of the Universite de Paris VI and the Centre de Sociologie de l'Innovation of the Ecole Nationale Superieure des Mines de Paris, and especially Michel Callón, Bruno Latour, and Jean-Francois Perrot, for their generous support during the preparation of the course and of this manuscript. Finally, we thank Leslie B. Hill for her unswerving patience, understanding, and excellent good nature. Nicholas M. Avouris and Les Gasser