Around ten years ago, when we were both PhD students, working on different but related aspects of artificial intelligence, we shared an office in the furthest corner of the Department of Computer Science at University College London. Our friendship began then, but our professional collaboration only really got going when we both left, one of us moving the few yards to the University of Westminster and the other further afield to the University of Warwick and later the University of Southampton. Nevertheless, we can trace back many of our inspirations to those days at UCL, in discussions with Derek Long, John Campbell, Maria Fox and John Wolstencroft, who all contributed to our initial enthusiasm for working in this area. On leaving UCL, however, we tried to bring our research interests together in the newly emerging area of agent-based systems, but found difficulties in communica tion with each other over basic terms and concepts, simply due to the immaturity of the field. In other words, the problems we had in finding a base on which to develop our ideas set us on a long path, over a number of years, resulting in our construction and refinement of a conceptual framework within which to define, analyse and ex plore different aspects of agents and multi-agents systems. This is the work reported in this book.
