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2000

Backbone Fragility and the Local Search Cost Peak

11 years 1 months ago
Backbone Fragility and the Local Search Cost Peak
The local search algorithm WSat is one of the most successful algorithms for solving the satisfiability (SAT) problem. It is notably effective at solving hard Random 3-SAT instances near the so-called `satisfiability threshold', but still shows a peak in search cost near the threshold and large variations in cost over different instances. We make a number of significant contributions to the analysis of WSat on high-cost random instances, using the recently-introduced concept of the backbone of a SAT instance. The backbone is the set of literals which are entailed by an instance. We find that the number of solutions predicts the cost well for small-backbone instances but is much less relevant for the large-backbone instances which appear near the threshold and dominate in the overconstrained region. We show a very strong correlation between search cost and the Hamming distance to the nearest solution early in WSat's search. This pattern leads us to introduce a measure of the ...
Josh Singer, Ian P. Gent, Alan Smaill
Added 18 Dec 2010
Updated 18 Dec 2010
Type Journal
Year 2000
Where JAIR
Authors Josh Singer, Ian P. Gent, Alan Smaill
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