An MTBDD-Based Implementation of Forward Reachability for Probabilistic Timed Automata

Abstract

Abstract. Multi-Terminal Binary Decision Diagrams (MTBDDs) have been successfully applied in symbolic model checking of probabilistic systems. In this paper we propose an encoding method for Probabilistic Timed Automata (PTA) based on MTBDDs. The timing information is encoded via placeholders stored in the MTBDDs that are independent of how the timing information is represented. Using the Colorado University Decision Diagrams (CUDD) package, an experimental model checker is implemented, which supports probabilistic reachability model checking via the forward algorithm. We use Difference Bound Matrices (DBMs) and Difference Decision Diagrams (DDDs) for representing timing information and present experimental results on three case studies. Our key contribution is a general placeholder encoding method for Probabilistic Timed Automata and an experimental MTBDD-based model checker which has been partly integrated with PRISM. This is the first symbolic implementation of the forward probabilistic reachability algorithm.

A model-checking-based approach to risk analysis in supply chain consolidations

“…Also, simulation-based approaches in general have a better scalability than formal analysis approaches like ours. This is because simulation-based approach explores only one execution path at a time, whereas our model-checking-based approach checks all the possible execution pathes, although our underlying model checker does so efficiently using symbolic technique [17].…”

“…Our choice of using probabilistic model checking as underlying analysis technology brings us several benefits: first, recent advances in probabilistic model checking provide efficient symbolic decision procedures. Symbolic probabilistic model checkers such as PRISM [9] use sophisticated symbolic techniques including Multi-Terminal Binary Decision Diagrams (MTBDD) [17]. By using probabilistic model checking, we are able to leverage the benefits of efficient decision procedures developed for verifying large-scale computer-based systems.…”