Optimizing symbolic model checking for statecharts

Symbolic model checking based on binary decision diagrams is a powerful formal verification technique for reactive systems. In this paper, we present various optimizations for improving the time and space efficiency of symbolic modal checking for systems specified as statecharts. We used these techniques in our analyses of the models of a collision avoidance system and a fault-tolerant electrical power distribution (EPD) system, both used on commercial aircraft. The techniques together reduce the time and space requirements by orders of magnitude, making feasible some analysis that was previously intractable. We also elaborate on the results of verifying the EPD model. The analysis disclosed subtle modeling and logical flaws not found by simulation.