Partial Order Reduction for State/Event Systems

Abstract

State/Event Linear Temporal Logic (SE-LTL) provides a concise and intuitive way to express properties incorporating both states and events. However, as SE-LTL is not preserved under classical stutter-equivalence, conventional Partial Order Reduction (POR) cannot be directly used to check them. In this paper, we propose a novel technique to exploit POR for checking SE-LTL. This technique detects a “state part” of a Buchi automaton (BA) translated from an SE-LTL formula. POR is integrated into the construction of the synchronous products of BAs and Labeled Kripke Structures (LKS), where “state parts” direct the use of POR. The integrated POR modifies conventional POR by introducing an identification of visible actions with respect to events. In addition, we compare our technique with the existing POR for weak SE-LTL and give a method to combine them to obtain more reduction. We have implemented our technique in the SPIN model checker. The experimental results illustrate the potential of the technique for reduction compared with pure state-based POR and SE-LTL model checking without POR.