This book is about the verification of reactive systems. A reactive system is a system that maintains an ongoing interaction with its environment, as opposed to computing some final value on termination. The family of reactive systems includes many classes of programs whose correct and reliable construction is con sidered to be particularly challenging, including concurrent programs, embedded and process control programs, and operating systems. Typical examples of such systems are an air traffic control system, programs controlling mechanical devices such as a train, or perpetually ongoing processes such as a nuclear reactor. With the expanding use of computers in safety-critical areas, where failure is potentially disastrous, correctness is crucial. This has led to the introduction of formal verification techniques, which give both users and designers of software and hardware systems greater confidence that the systems they build meet the desired specifications. Framework The approach promoted in this book is based on the use of temporal logic for specifying properties of reactive systems, and develops an extensive verification methodology for proving that a system meets its temporal specification. Reactive programs must be specified in terms of their ongoing behavior, and temporal logic provides an expressive and natural language for specifying this behavior. Our framework for specifying and verifying temporal properties of reactive systems is based on the following four components: 1. A computational model to describe the behavior of reactive systems. The model adopted in this book is that of a Fair Transition System (FTS).

Self-concept and coping behaviour are important aspects of development in adolescence. Despite their developmental significance, however, the two areas have rarely been considered in relation to each other. This book is the first in which the two areas are brought together; it suggests that this interaction can open the way to new possibilities for further research and to new implications for applied work with adolescents. Two separate chapters review research carried out in each of the areas. These are followed by a series of more empirically focussed chapters in which issues such as changes in relationship patterns, difficult school situations, leaving school, use of leisure, anxiety and suicidal behaviour are examined in the context of self-concept and coping. The final chapter seeks to identify some of the central themes emerging from this work and discusses possible research and applied implications.