This volume gives the proceedings of the conference CONCUR '90. This is the first conference organized by ESPRIT Basic Research Action 3006, CONCUR (Theories of Concurrency: Unification and Extension), started in September 1989. The principal aims of the action are to explore the relationships among the different approaches to algebraic concurrency theory, and to develop a formalism applicable to a wide range of case studies. The articles in this volume describe the state of the art in concurrency, the theory of communicating concurrent (or distributed) systems.

This volume gives the proceedings of the conference CONCUR '90. This is the first conference organized by ESPRIT Basic Research Action 3006, CONCUR (Theories of Concurrency: Unification and Extension), started in September 1989. The principal aims of the action are to explore the relationships among the different approaches to algebraic concurrency theory, and to develop a formalism applicable to a wide range of case studies. The articles in this volume describe the state of the art in concurrency, the theory of communicating concurrent (or distributed) systems.