Bertrand Mazure

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In this paper, an efficient heuristic allowing one to localize inconsistent kernels in propositional knowledge‐bases is described. Then, it is shown that local search techniques can boost the performance of logically complete methods for SAT. More precisely, local search techniques can be used to guide the branching strategy of logically complete techniques(More)
In this paper, a new pre-processing step is proposed in the resolution of SAT instances, that recovers and exploits structural knowledge that is hidden in the CNF. It delivers an hybrid formula made of clauses together with a set of equations of the form y = f(x1, . . . , xn) where f is a standard connective operator among (∨, ∧, ⇔) and where y and xi are(More)
In this paper tabu search for SAT is investi gated from an experimental point of view To this end TSAT a basic tabu search algorithm for SAT is introduced and compared with Selman et al Random Walk Strategy GSAT procedure in short RWS GSAT TSAT does not involve the ad ditional stochastic process of RWS GSAT This should facilitate the understanding of why(More)
In this paper, a new complete technique to compute Maximal Satisfiable Subsets (MSS) and Minimally Unsatisfiable Subformulas (MUS) of sets of Boolean clauses is introduced. The approach improves the currently most efficient complete technique in several ways. It makes use of the powerful concept of critical clause and of a computationally inexpensive local(More)
SAT is probably one of the most-studied constraint satisfaction problems. In this paper, a new hybrid technique based on local search is introduced in order to approximate and extract minimally unsatisfiable subformulas (in short, MUSes) of unsatisfiable SAT instances. It is based on an original counting heuristic grafted to a local search algorithm, which(More)
In this paper, a new complete technique to compute Maximal Satisfiable Subsets (MSSes) and Minimally Unsatisfiable Subformulas (MUSes) of sets of Boolean clauses is introduced. The approach improves the currently most efficient complete technique in several ways. It makes use of the powerful concept of critical clause and of a computationally inexpensive(More)
These last years, the issue of locating and explaining contradictions inside sets of propositional clauses has received a renewed attention due to the emergence of very efficient SAT solvers. In case of inconsistency, many such solvers merely conclude that no solution exists or provide an upper approximation of the subset of clauses that are contradictory.(More)
In this paper, we propose a new dynamic management policy of the learnt clause database in modern SAT solvers. It is based on a dynamic freezing and activation principle of the learnt clauses. At a given search state, using a relevant selection function, it activates the most promising learnt clauses while freezing irrelevant ones. In this way, clauses(More)
The concepts of MSS (Maximal Satisfiable Subset) and CoMSS (also called Minimal Correction Subset) play a key role in many A.I. approaches and techniques. In this paper, a novel algorithm for partitioning a Boolean CNF formula into one MSS and the corresponding CoMSS is introduced. Extensive empirical evaluation shows that it is more robust and more(More)