Approximation algorithms for MAX SAT: Yannakakis vs. Goemans-Williamson

MAX SAT (the maximum satisfiability problem) is stated as follows: given a set of clauses with weights, find a truth assignment that maximizes the sum of the weights of the satisfied clauses. In this paper, we consider approximation algorithms for MAX SAT proposed by Yannnkakis and Goemans-Williamson and present an approximation algorithm which is an improvement of Yannakakis' algorithm. Although Yannakakis' original algorithm has no better performance guarantee than Goemans-Williamson, our improved algorithm has a better performance guarantee and leads to a 0.770 approximation algorithm.