Directed explicit-state model checking in the validation of communication protocols

Abstract

The success of model checking is largely based on its ability to efficiently locate errors in software designs. If an error is found, a model checker produces a trail that shows how the error state can be reached, which greatly facilitates debugging. However, while current model checkers find error states efficiently, the counterexamples are often unnecessarily lengthy, which hampers error explanation. This is due to the use of "naive" search algorithms in the state space exploration. In this paper we present approaches to the use of heuristic search algorithms in explicit-state model checking. We present the class of A * directed search algorithms and propose heuristics together with bitstate compression techniques for the search of safety property violations. We achieve great reductions in the length of the error trails, and in some instances render problems analyzable by exploring a much smaller number of states than standard depth-first search. We then suggest an improvement of the nested depth-first search algorithm and show how it can be used together with A * to improve the search for liveness property violations. Our approach to directed explicit-state model checking has been implemented in a tool set called HSF-SPIN. We provide experimental results from the protocol validation domain using HSF-SPIN.

Strength-Based Decomposition of the Property Büchi Automaton for Faster Model Checking

“…This is done using fixed points on symbolic set of states, and amounts to performing a BFS-based emptiness check. Whether based on nested DFS or SCC, explicit or symbolic, these emptinesscheck procedures can be simplified according to the strength of the automaton representing the property to check [2,13,6,23,1].…”

“…In most of the approaches suggested so far the improvements have only concerned (inherently) weak or terminal automata: if an automaton contains at least one strong SCC, a general emptiness check is required, even if it also contains SCCs of inferior strengths. However Edelkamp et al [13] have suggested to consider the strengths of the SCCs to limit the scope of the nested DFS to the strong SCCs.…”

“…They also make it easier to apply other reduction such as partial order reductions [18], and they tend to produce smaller counterexamples [13].…”

Subsumer-First: Steering Symbolic Reachability Analysis

“…Directed model checking techniques [10,11] try to direct the state space search to avoid the potential blowup faced by uninformed model checking techniques. Various heuristic strategies [9,13,15] have been proposed for searching the state space efficiently.…”

Large-Scale Directed Model Checking LTL

“…Directed explicit-state model checking [13] enhances the error-reporting capabilities of model checkers. The application of guided search for checking liveness properties is restricted to the reduction of trails [14].…”