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    Super Strong ETH is False for Random kk-SAT

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    It has been hypothesized that kk-SAT is hard to solve for randomly chosen instances near the "critical threshold", where the clause-to-variable ratio is 2kln⁑2βˆ’ΞΈ(1)2^k \ln 2-\theta(1). Feige's hypothesis for kk-SAT says that for all sufficiently large clause-to-variable ratios, random kk-SAT cannot be refuted in polynomial time. It has also been hypothesized that the worst-case kk-SAT problem cannot be solved in 2n(1βˆ’Ο‰k(1)/k)2^{n(1-\omega_k(1)/k)} time, as multiple known algorithmic paradigms (backtracking, local search and the polynomial method) only yield an 2n(1βˆ’1/O(k))2^{n(1-1/O(k))} time algorithm. This hypothesis has been called the "Super-Strong ETH", modeled after the ETH and the Strong ETH. Our main result is a randomized algorithm which refutes the Super-Strong ETH for the case of random kk-SAT, for any clause-to-variable ratio. Given any random kk-SAT instance FF with nn variables and mm clauses, our algorithm decides satisfiability for FF in 2n(1βˆ’Ξ©(log⁑k)/k)2^{n(1-\Omega(\log k)/k)} time, with high probability. It turns out that a well-known algorithm from the literature on SAT algorithms does the job: the PPZ algorithm of Paturi, Pudlak, and Zane (1998).Comment: 15 page
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