Approximate Symbolic Reachability of Networks of Transition Systems

Symbolic reachability analysis of networks of state transition systems present special optimization opportunities that are not always available in monolithic state transition systems. These optimizations can potentially allow scaling of reachability analysis to much larger networks than can be handled using existing techniques. In this paper, we discuss a set of techniques for efficient approximate reachability analysis of large networks of small state transition systems with local interactions, and analyse their relative precision and performance in a BDD-based tool. We use overlapping projections to represent the state space, and discuss optimizations that significantly limit the set of variables in the support set of BDDs that must be manipulated to compute the image of each projection due to a transition of the system. The ideas presented in this paper have been implemented in a BDDbased symbolic reachability analyser built using the public-domain symbolic model checking framework of NuSMV. We report experimental results on a set of benchmarks that demonstrate the effectiveness of our approach over existing techniques using overlapping projections.