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CNF propositional satis ability SAT is a special kind of the more general Constraint Satisfaction Problem CSP While look back techniques appear to be of little use to solve hard random SAT problems it is supposed that they are necessary to solve hard structured SAT problems In this paper we propose a very simple DPL procedure called Satz which only employs(More)
The diagnosis of a discrete-event system is the problem of computing possible behaviors of the system given observations of the actual behavior, and testing whether the behaviors are normal or faulty. We show how the diagnosis problems can be translated into the propositional satisfiability problem (SAT) and solved by algorithms for SAT. Our experiments(More)
In the satisfiability domain, it is well-known that a SAT algorithm may solve a problem instance easily and another instance hardly, whilst these two instances are equivalent CNF encodings of the original problem. Moreover, different algorithms may disagree on which encoding makes the problem easier to solve. In this paper, we focus on the CNF encoding of(More)
In recent years, dynamic local search (DLS) clause weighting algorithms have emerged as the local search state-of-the-art for solving propositional satisfiability problems. However, most DLS algorithms require the tuning of domain dependent parameters before their performance becomes competitive. If manual parameter tuning is impractical then various(More)
We present a new and more efficient heuristic by restricting lookahead saturation (LAS) with NVO (neighbourhood variable ordering) and DEW (dynamic equality weighting). We report on the integration of this heuristic in Satz, a high-performance SAT solver, showing empirically that it significantly improves the performance on an extensive range of benchmark(More)
We present a variant of the Weighted Maximum Satisfiability Problem (Weighted Max-SAT), which is a modeling of the Semiring Constraint Satisfaction framework. We show how to encode a Semiring Constraint Satisfaction Problem (SCSP) into an instance of a propositional Weighted Max-SAT, and call the encoding Weighted Semiring Max-SAT (WS-Max-SAT). The clauses(More)
We propose a novel algorithm for the diagnosis of systems modelled as discrete event systems. Instead of computing all paths of the model that are consistent with the observations, we use a two-level approach: at the first level diagnostic questions are generated in the form does there exist a path from a given subset that is consistent with the(More)
The DPLL (Davis-Putnam-Logemann-Loveland) procedure is one of the most effective methods for solving SAT problems. It is well known that its efficiency depends on the choice of the branching rule. Different branching rules are proposed in the literature. Unit propagation look-ahead (UPLA) branching rule was one of the main improvements in the DPLL procedure(More)