A New Algorithm for MAX-2-SAT

Recently there was a significant progress in proving (exponential-time) worst-case upper bounds for the propositional satisfiability problem (SAT) and related problems. In particular, for MAX-2-SAT Niedermeier and Rossmanith recently presented an algorithm with worstcase upper bound O(K ċ2K/2.88...), and the bound O(K ċ2K/3.44...) is implicit from the paper by Bansal and Raman (K is the number of clauses). In this paper we improve this bound to p(K)2K2/4, where K2 is the number of 2-clauses, and p is a polynomial. In addition, our algorithm and the proof are much simpler than the previous ones. The key ideas are to use the symmetric flow algorithm of Yannakakis and to count only 2-clauses (and not 1-clauses).

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