Greedy Algorithms for the Maximum Satisfiability Problem: Simple Algorithms and Inapproximability Bounds

Autor: David P. Williamson, Matthias Poloczek, Anke van Zuylen, Georg Schnitger
Rok vydání: 2017
Předmět:
Zdroj: SIAM Journal on Computing. 46:1029-1061
ISSN: 1095-7111
0097-5397
DOI: 10.1137/15m1053369
Popis: We give a simple, randomized greedy algorithm for the maximum satisfiability problem (MAX SAT) that obtains a $\frac{3}{4}$-approximation in expectation. In contrast to previously known $\frac{3}{4}$-approximation algorithms, our algorithm does not use flows or linear programming. Hence we provide a positive answer to a question posed by Williamson in 1998 on whether such an algorithm exists. Moreover, we show that Johnson's greedy algorithm cannot guarantee a $\frac{3}{4}$-approximation, even if the variables are processed in a random order. Thereby we partially solve a problem posed by Chen, Friesen, and Zheng in 1999. In order to explore the limitations of the greedy paradigm, we use the model of priority algorithms of Borodin, Nielsen, and Rackoff. Since our greedy algorithm works in an online scenario where the variables arrive with their set of undecided clauses, we wonder if a better approximation ratio can be obtained by further fine-tuning its random decisions. For a particular information model ...
Databáze: OpenAIRE