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AllDifferent-based Filtering for Subgraph Isomorphism
"... The subgraph isomorphism problem involves deciding if there exists a copy of a pattern graph in a target graph. This problem may be solved by a complete tree search combined with filtering techniques that aim at pruning branches that do not contain solutions. We introduce a new filtering algorithm b ..."
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Cited by 12 (4 self)
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The subgraph isomorphism problem involves deciding if there exists a copy of a pattern graph in a target graph. This problem may be solved by a complete tree search combined with filtering techniques that aim at pruning branches that do not contain solutions. We introduce a new filtering algorithm based on local all different constraints. We show that this filtering is stronger than other existing filterings — i.e., it prunes more branches — and that it is also more efficient —i.e., it allows one to solve more instances quicker.
An alternative to sat-based approaches for bit-vectors
- In Tools and Algorithms for the Construction and Analysis (TACAS’10
, 2010
"... Abstract. The theory BV of bit-vectors, i.e. fixed-size arrays of bits equipped with standard low-level machine instructions, is becoming very popular in formal verification. Standard solvers for this theory are based on a bit-level encoding into propositional logic and SAT-based resolution techniqu ..."
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Cited by 5 (2 self)
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Abstract. The theory BV of bit-vectors, i.e. fixed-size arrays of bits equipped with standard low-level machine instructions, is becoming very popular in formal verification. Standard solvers for this theory are based on a bit-level encoding into propositional logic and SAT-based resolution techniques. In this paper, we investigate an alternative approach based on a word-level encoding into bounded arithmetic and Constraint Logic Programming (CLP) resolution techniques. We define an original CLP framework (domains and propagators) dedicated to bitvector constraints. This framework is implemented in a prototype and thorough experimental studies have been conducted. The new approach is shown to perform much better than standard CLP-based approaches, and to considerably reduce the gap with the best SAT-based BV solvers. 1
Proteus: A Hierarchical Portfolio of Solvers and Transformations
"... Abstract. In recent years, portfolio approaches to solving SAT prob-lems and CSPs have become increasingly common. There are also a num-ber of different encodings for representing CSPs as SAT instances. In this paper, we leverage advances in both SAT and CSP solving to present a novel hierarchical p ..."
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Cited by 4 (2 self)
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Abstract. In recent years, portfolio approaches to solving SAT prob-lems and CSPs have become increasingly common. There are also a num-ber of different encodings for representing CSPs as SAT instances. In this paper, we leverage advances in both SAT and CSP solving to present a novel hierarchical portfolio-based approach to CSP solving, which we call Proteus, that does not rely purely on CSP solvers. Instead, it may decide that it is best to encode a CSP problem instance into SAT, selecting an appropriate encoding and a corresponding SAT solver. Our experimental evaluation used an instance of Proteus that involved four CSP solvers, three SAT encodings, and six SAT solvers, evaluated on the most chal-lenging problem instances from the CSP solver competitions, involving global and intensional constraints. We show that significant performance improvements can be achieved by Proteus obtained by exploiting alter-native view-points and solvers for combinatorial problem-solving. 1
Author manuscript, published in "17th International Conference on Principles and Practice of Constraint Programming (CP'11), Perugla: Italy (2011)" A CSP solver focusing on FAC variables ⋆
, 2013
"... Abstract. The contribution of this paper is twofold. On the one hand, it introduces a concept of FAC variables in discrete Constraint Satisfaction Problems (CSPs). FAC variables can be discovered by local search techniques and powerfully exploited by MAC-based methods. On the other hand, a novel syn ..."
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Abstract. The contribution of this paper is twofold. On the one hand, it introduces a concept of FAC variables in discrete Constraint Satisfaction Problems (CSPs). FAC variables can be discovered by local search techniques and powerfully exploited by MAC-based methods. On the other hand, a novel synergetic combination schema between local search paradigms, generalized arcconsistency and MAC-based algorithms is presented. By orchestrating a multipleway flow of information between these various fully integrated search components, it often proves more competitive than the usual techniques on most classes of instances. 1
