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...