Title
A Probabilistic Algorithm for k -SAT Based on Limited Local Search and Restart.
Abstract
A simple probabilistic algorithm for solving the NP-complete problem k-SAT is reconsidered. This algorithm follows a well-known local-search paradigm: randomly guess an initial assignment and then, guided by those clauses that are not satisfied, by successively choosing a random literal from such a clause and changing the corresponding truth value, try to find a satisfying assignment. Papadimitriou [11] introduced this random approach and applied it it) the case of 2-SAT, obtaining an expected O(n(2)) time bound. The novelty here is to restart (lie algorithm after 3n unsuccessful steps of local search. The analysis shows that for any satisfiable k-CNF formula with n variables, the expected number of repetitions until a satisfying assignment is found this way is (2 . (k - 1)/k)(n). Thus, for 3-SAT the algorithm presented here has a complexity which is within a polynomial factor of (4/3)(n). This is the fastest and also the simplest among those algorithms known up to date for 3-SAT achieving an o(2(n)) time bound. Also, the analysis is quite simple compared with other such algorithms considered before.
Year
DOI
Venue
2002
10.1007/s00453-001-0094-7
Algorithmica
Keywords
Field
DocType
polynomial factorization,local search,satisfiability,probabilistic algorithm,np complete problem
Discrete mathematics,Randomized algorithm,Combinatorics,Polynomial,Boolean satisfiability problem,Propositional calculus,Probabilistic analysis of algorithms,Probability distribution,Expected value,Local search (optimization),Mathematics
Journal
Volume
Issue
ISSN
32
4
0178-4617
Citations 
PageRank 
References 
38
1.76
5
Authors
1
Name
Order
Citations
PageRank
Uwe Schöning1998105.69