Abstract

. Despite recent advances in model checking and in adapting model checking techniques to software, the state explosion problem remains a major hurdle in applying model checking to software. Recent work in automated program abstraction has shown promise as a means of scaling model checking to larger systems. Most common abstraction techniques compute an upper approximation of the original program. Thus, when a specification is found true for the abstracted program, it is known to be true for the original program. Finding a specification to be false, however, is inconclusive since the specification may be violated on a behavior in the abstracted program which is not present in the original program. We have extended an explicit-state model checker, Java PathFinder (JPF), to analyze counter-examples in the presence of abstractions. We enhanced JPF to search for "feasible" counter-examples during model checking. Alternatively, an abstract counter-example can be used to guide the simulation of the concrete computation and thereby check feasibility of the counter-example. We demonstrate the effectiveness of these techniques on counter-examples from checks of several multi-threaded Java programs. 1

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