A Representative Function Approach to Symmetry Exploitation for CSP Refinement Checking

Abstract

Effective temporal logic model checking algorithms exist that exploit symmetries arising from parallel composition of multiple identical components. These algorithms often employ a function rep from states to representative states under the symmetries exploited. We adapt this idea to the context of refinement checking for the process algebra CSP. In so doing, we must cope with refinement-style specifications. The main challenge, though, is the need for access to sufficient local information about states to enable definition of a useful rep function, since compilation of CSP processes to Labelled Transition Systems (LTSs) renders state information a global property instead of a local one. Using a structured form of implementation transition system, we obtain an efficient symmetry exploiting CSP refinement checking algorithm, generalise it in two directions, and demonstrate all three variants on simple examples.