An action refinement operator for E-LOTOS with true concurrency

Action refinement is an important operation in the hierarchical synthesis of concurrent systems. We propose an action refinement operator for E-LOTOS, a standard process-algebraic language for formal specification of real-time, concurrent and reactive systems. As the first step towards giving E-LOTOS a multitude of refinement operators supporting a variety of strategies for event relationship inheritance, we propose an operator which seems both useful and simple to implement. When the operator is applied to an E-LOTOS process, it modifies its enhanced event structure, i.e. its recently defined true concurrency model. The operator allows multiple alternative implementations even for urgent events and properly reflects the fact that gate actions of E-LOTOS processes are in the general case abstractions of distributed data generation procedures.