This book will attempt to give a first synthesis of recent works con cerning reactive system design. The term "reactive system" has been introduced in order to at'oid the ambiguities often associated with by the term "real-time system," which, although best known and more sugges tive, has been given so many different meanings that it is almost in evitably misunderstood. Industrial process control systems, transporta tion control and supervision systems, signal-processing systems, are ex amples of the systems we have in mind. Although these systems are more and more computerized, it is sur...