The Asymptotic Order of the k-SAT Threshold

Dimitris Achlioptas; Cristopher Moore

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The Asymptotic Order of the k-SAT Threshold

Dimitris Achlioptas·Cristopher Moore

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Abstract

Form a random k-SAT formula on n variables by selecting uniformly and independently m=rn clauses out of all 2^k (n choose k) possible k-clauses. The Satisfiability Threshold Conjecture asserts that for each k there exists a constant r_k such that, as n tends to infinity, the probability that the formula is satisfiable tends to 1 if r < r_k and to 0 if r > r_k. It has long been known that 2^k / k < r_k < 2^k. We prove that r_k > 2^{k-1} \ln 2 - d_k, where d_k \to (1+\ln 2)/2. Our proof also allows a blurry glimpse of the ``geometry'' of the set of satisfying truth assignments, and a nearly exact location of the threshold for Not-All-Equal (NAE) k-SAT.

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Dimitris Achlioptas, Cristopher Moore. 2002-09-26. The Asymptotic Order of the k-SAT Threshold. https://arxiv.org/abs/cond-mat/0209622

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