Concurrent systems abound in human experience but their fully adequate conceptualization as yet eludes our most able thinkers. The COSY (ConcurrentSystem) notation and theory was developed in the last decade as one of a number of mathematical approaches for conceptualizing and analyzing concurrent and reactive systems. The COSY approach extends theconventional notions of grammar and automaton from formal language and automata theory to collections of "synchronized" grammars and automata, permitting system specification and analysis of "true" concurrency without reduction to non-determinism. COSY theory is developed to a great level of detail and constitutes the first uniform and self-contained presentationof all results about COSY published in the past, as well as including many new results. COSY theory is used to analyze a sufficient number of typical problems involving concurrency, synchronization and scheduling, to allow the reader to apply the techniques presented tosimilar problems. The COSY model is also related to many alternative models of concurrency, particularly Petri Nets, Communicating Sequential Processes and the Calculus of Communicating Systems.

This collection of papers arose from a series of lectures for workers in computer science and other disciplines. The lectures were intended to familiarize them with some of the most exciting advanced computer based systems for the conceptualization, design, implementation, simulation, and logical analysis of applications in these disciplines. The collection presents some strong motivational points for the use of theory based systems in the areas of functional programming, concurrency, simulation, and automated reasoning, highlighting some of their advantages and disadvantages relative to conventional systems. The papers are mostly the work of individuals who were among the originators of the systemspresented. The volume is intended as a contribution to narrowing the learning gap facing conventional computer users when they wish to use advanced theory based systems. The papers are meant for a wide audience and should not require great mathematical sophistication for their comprehension. The papers contain numerous references for those wishing to pursue a topic in greater depth.