Limited discrepancy search revisited

Prosser, P. and Unsworth, C. (2011) Limited discrepancy search revisited. Journal of Experimental Algorithmics, 16, Article 1.6. (doi: 10.1145/1963190.2019581)

Abstract

Harvey and Ginsberg's limited discrepancy search (LDS) is based on the assumption that costly heuristic mistakes are made early in the search process. Consequently, LDS repeatedly probes the state space, going against the heuristic (i.e., taking discrepancies) a specified number of times in all possible ways and attempts to take those discrepancies as early as possible. LDS was improved by Richard Korf, to become improved LDS (ILDS), but in doing so, discrepancies were taken as late as possible, going against the original assumption. Many subsequent algorithms have faithfully inherited Korf's interpretation of LDS, and take discrepancies late. This then raises the question: Should we take our discrepancies late or early? We repeat the original experiments performed by Harvey and Ginsberg and those by Korf in an attempt to answer this question. We also investigate the early stopping condition of the YIELDS algorithm, demonstrating that it is simple, elegant and efficient.

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Unsworth, Dr Chris and Prosser, Dr Patrick
• Authors: Prosser, P., and Unsworth, C.
• College/School: College of Science and Engineering > School of Computing Science
• Journal Name: Journal of Experimental Algorithmics
• ISSN: 1084-6654