Guarded operations, refinement and simulation

Abstract

Simulation rules have long been used as an effective computational means to decide refinement relations in state-based formalisms. Here we investigate how they might be amended so as to decide the event-based notion of singleton failures refinement of abstract data types or processes that have operations with a "guarded" interpretation. As the results presented here and found elsewhere in the literature are so sensitive to the details of the definitions used, we have machine-checked our results.