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| Content Provider | ACM Digital Library |
|---|---|
| Author | Maneva, Elitza Mossel, Elchanan Wainwright, Martin J. |
| Copyright Year | 2007 |
| Abstract | This article provides a new conceptual perspective on survey propagation, which is an iterative algorithm recently introduced by the statistical physics community that is very effective in solving random $\textit{k}-SAT$ problems even with densities close to the satisfiability threshold. We first describe how any SAT formula can be associated with a novel family of Markov random fields (MRFs), parameterized by a real number ρ ∈ [0, 1]. We then show that applying belief propagation---a well-known “message-passing” technique for estimating marginal probabilities---to this family of MRFs recovers a known family of algorithms, ranging from pure survey propagation at one extreme (ρ = 1) to standard belief propagation on the uniform distribution over SAT assignments at the other extreme (ρ = 0). Configurations in these MRFs have a natural interpretation as partial satisfiability assignments, on which a partial order can be defined. We isolate $\textit{cores}$ as minimal elements in this partial ordering, which are also fixed points of survey propagation and the only assignments with positive probability in the MRF for ρ = 1. Our experimental results for $\textit{k}$ = 3 suggest that solutions of random formulas typically do not possess non-trivial cores. This makes it necessary to study the structure of the space of partial assignments for ρ < 1 and investigate the role of assignments that are very close to being cores. To that end, we investigate the associated lattice structure, and prove a weight-preserving identity that shows how any MRF with ρ > 0 can be viewed as a “smoothed” version of the uniform distribution over satisfying assignments (ρ = 0). Finally, we isolate properties of Gibbs sampling and message-passing algorithms that are typical for an ensemble of $\textit{k}-SAT$ problems. |
| File Format | |
| ISSN | 00045411 |
| e-ISSN | 1557735X |
| DOI | 10.1145/1255443.1255445 |
| Journal | Journal of the ACM (JACM) |
| Volume Number | 54 |
| Issue Number | 4 |
| Language | English |
| Publisher | Association for Computing Machinery (ACM) |
| Publisher Date | 2007-07-01 |
| Publisher Place | New York |
| Access Restriction | One Nation One Subscription (ONOS) |
| Subject Keyword | k-SAT Gibbs sampling Markov random field Satisfiability problems Belief propagation Factor graph Message-passing Sum-product Survey propagation |
| Content Type | Text |
| Resource Type | Article |
| Subject | Hardware and Architecture Information Systems Control and Systems Engineering Artificial Intelligence Software |
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