We define a new class of games, called backtracking games. Backtracking games are essentially parity games with an additional rule allowing players, under certain conditions, to return to an earlier position in the play and revise a choice. This new feature makes backtracking games more powerful than parity games. As a consequence, winning strategies become more complex objects and computationa...

The standard technique for LTL model checking (M φ) consists on translating the negation of the LTL specification, φ, into a Büchi automaton Aφ, and then on checking if the product M Aφ has an empty language. The efforts to maximize the efficiency of this process have so far concentrated on developing translation algorithms producing Büchi automata which are “as small as possible”, under the im...

Model checking is a powerful and widespread technique for the verification of finite distributed systems. However, the main hindrance for wider application of this technique is the well-known state explosion problem. During the last two decades, numerous techniques have been proposed to cope with the state explosion problem in order to get a manageable state space. Among them, on-the-fly modelc...

We apply Monte Carlo model checking to the Needham-Schroeder public key authentication protocol. The Monte Carlo approach uses random sampling of “lassos” (reachable cycles) to compute an estimate of the weighted expectation that a system S satisfies an LTL formula φ within a factor of 1 ± with probability at least 1 − δ. It does so using a number of samples N that is optimal to within a consta...

Automated methods for an undecidable class of verification problems cannot be complete (terminate for every correct program). We therefore consider a new kind of quality measure for such methods, which is completeness relative to a (powerful but unrealistic) oraclebased method. More precisely, we ask whether an often implemented method known as “software model checking with abstraction refineme...

We introduce tree-width for first order formulae φ, fotw(φ). We show that computing fotw is fixed-parameter tractable with parameter fotw. Moreover, we show that on classes of formulae of bounded fotw, model checking is fixed parameter tractable, with parameter the length of the formula. This is done by translating a formula φ with fotw(φ) < k into a formula of the k-variable fragment L of firs...

Model checking [3] is a very popular paradigm for automatic verification of properties of finite state systems like those defined by circuits or communication protocols. A system is interpreted as a finite state labeled transition system or equivalently as a finite Kripke structure. If sys contains k concurrent components, each with m states, then the Kripke structure described by sys may have ...

Model Repair George Chatzieleftheriou, Borzoo Bonakdarpour, Scott A. Smolka, and Panagiotis Katsaros 1 Department of Informatics, Aristotle University of Thessaloniki 54124 Thessaloniki, Greece 2 School of Computer Science, University of Waterloo 200 University Avenue West Waterloo N2L3G1, Canada 3 Department of Computer Science, Stony Brook University Stony Brook, NY 11794-4400, USA Abstract. ...

This paper describes a technique of inductive proof based on model checking. It differs from previous techniques that combine induction and model checking in that the proof is fully mechanically checked and temporal variables (process identifiers, for example) may be natural numbers. To prove ∀n.φ(n) inductively, the predicate φ(n − 1) ⇒ φ(n) must be proved for all values of the parameter n. It...