Distributed Verification of Modular Systems

The use of distributed or parallel processing gained interest in the recent years to fight the state space explosion problem. Many industrial systems are described with large models, and the state space being even larger, it does not fit completely into the memory of a single computer. To avoid the high space requirement, several reduction techniques have been proposed: modular verification, partial order reductions, symmetries, using symbolic or compact representations like BDDs. Another way to alleviate the state space explosion problem is to use modular analysis, which takes advantage of the modular structure of a system specification, particularly for systems where the modules exhibit strong cohesion and weak coupling. In this paper, we propose to combine distributed processing and modular analysis to perform verification of basic behavioural properties such as reachability, deadlock states, liveness, and home states and their distributed analysis for modular systems. Each module is assigned to a process which explores independently the internal activity of the module, allowing a significant reduction in the size of the state space rather than in an interleaved fashion.