Joël Ouaknine

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We present a framework for model checking concurrent software systems which incorporates both states and events. Contrary to other state/event approaches, our work also integrates two powerful verification techniques, counterexample-guided abstraction refinement and compositional reasoning. Our specification language is a state/event extension of linear(More)
We study data nets, a generalisation of Petri nets in which tokens carry data from linearlyordered infinite domains and in which whole-place operations such as resets and transfers are possible. Data nets subsume several known classes of infinite-state systems, including multiset rewriting systems and polymorphic systems with arrays. We show that(More)
Metric temporal logic (MTL) is a prominent specification formalism for real-time systems. In this paper, we show that the satisfiability problem for MTL over finite timed words is decidable, with non-primitive recursive complexity. We also consider the model-checking problem for MTL: whether all words accepted by a given Alur-Dill timed automaton satisfy a(More)
For every finite model M and an LTL property φ, there exists a number CT (the Completeness Threshold) such that if there is no counterexample to φ in M of length CT or less, then M |= φ. Finding this number, if it is sufficiently small, offers a practical method for making Bounded Model Checking complete. We describe how to compute an over-approximation to(More)
ion and Counterexample-Guided Refinement in Model Checking of Hybrid Systems∗ Edmund Clarke, Ansgar Fehnker, Zhi Han, Bruce Krogh, Joël Ouaknine, Olaf Stursberg, Michael Theobald 1 Computer Science Department, Carnegie Mellon University, Pittsburgh, PA 15213, USA 2 Electrical and Computer Engineering, Carnegie Mellon University, Pittsburgh, PA 15213, USA 3(More)
Sudoku is a very simple and well-known puzzle that has achieved international popularity in the recent past. This paper addresses the problem of encoding Sudoku puzzles into conjunctive normal form (CNF), and subsequently solving them using polynomial-time propositional satisfiability (SAT) inference techniques. We introduce two straightforward SAT(More)
We consider the language inclusion problem for timed automata: given two timed automata A and B, are all the timed traces accepted by B also accepted by A? While this problem is known to be undecidable, we show here that it becomes decidable if A is restricted to having at most one clock. This is somewhat surprising, since it is well-known that there exist(More)
Metric Temporal Logic (MTL) is a prominent specification formalism for realtime systems. In this paper, we show that the satisfiability problem for MTL over finite timed words is decidable, with non-primitive recursive complexity. We also consider the model-checking problem for MTL: whether all words accepted by a given Alur-Dill timed automaton satisfy a(More)
There has been considerable progress in the domain of software verification over the last few years. This advancement has been driven, to a large extent, by the emergence of powerful yet automated abstraction techniques such as predicate abstraction. However, the state-space explosion problem in model checking remains the chief obstacle to the practical(More)
In 2004, Berdine, Calcagno and O’Hearn introduced a fragment of separation logic that allows for reasoning about programs with pointers and linked lists. They showed that entailment in this fragment is in coNP, but the precise complexity of this problem has been open since. In this paper, we show that the problem can actually be solved in polynomial time.(More)