An Evaluation of Metro Express

We study Express, a system that uses template semantics to map specifications to SMV models. We investigate the efficiency of the generated SMV models. We consider two case studies and compare manually created SMV models with models generated by Express. The generated models are more complex and have larger state spaces, and consequently longer verification times. We also analyze the effect of using different optimization schemes in Cadence SMV. Interestingly, some of the optimizations are more applicable to the generated models and made verification of the generated models outperform the manually created models for some queries. However, considering the best case for each model, the manually created model always outperforms the generated model. We propose some optimizations that could be used to improve dramatically the efficiency of the models generated by Express. We estimate the magnitude of improvements that such optimizations can provide.