1 research outputs found

    Deterministic search for CNF satisfying assignments in almost polynomial time

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    We consider the fundamental derandomization problem of deterministically finding a satisfying assignment to a CNF formula that has many satisfying assignments. We give a deterministic algorithm which, given an nn-variable poly(n)\mathrm{poly}(n)-clause CNF formula FF that has at least ε2n\varepsilon 2^n satisfying assignments, runs in time nO~(loglogn)2 n^{\tilde{O}(\log\log n)^2} for ε1/polylog(n)\varepsilon \ge 1/\mathrm{polylog}(n) and outputs a satisfying assignment of FF. Prior to our work the fastest known algorithm for this problem was simply to enumerate over all seeds of a pseudorandom generator for CNFs; using the best known PRGs for CNFs [DETT10], this takes time nΩ~(logn)n^{\tilde{\Omega}(\log n)} even for constant ε\varepsilon. Our approach is based on a new general framework relating deterministic search and deterministic approximate counting, which we believe may find further applications
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