DMCA
Lightweight Arc-Consistency Algorithms (2003)
Cached
Download Links
| Citations: | 6 - 2 self |
BibTeX
@MISC{Dongen03lightweightarc-consistency,
author = {M. R. C. Van Dongen},
title = {Lightweight Arc-Consistency Algorithms},
year = {2003}
}
Share
 |
 |
 |
 |
||
OpenURL
Abstract
Arc-consistency algorithms are the workhorse of many backtrack algorithms. Most research on arc-consistency algorithms is focusing on the design of algorithms that are optimal when it comes to worst case scenarios. This report will provide experimental evidence that, despite common belief to the contrary, the ability to deal efficiently with such worst case scenarios may not be a prerequisite for solving quickly. It will compare on the one hand AC-2001 , which has an optimal worst case time-complexity and is considered efficient, and on the other AC-3 d , which is not optimal when it comes to its worst case time-complexity, but which has a better space-complexity than AC-2001. Both algorithms will be compared for MAC search and for stand alone arc-consistency (the task of making a single CSP arc-consistent). For stand alone arc-consistency AC-3 d is the better algorithm when it comes to time but there is no clear winner when it comes to minimising the number of checks. For search the results are more interesting. MAC-2001 is by far the better algorithm when it comes to minimising the number of checks. However, MAC-3 d is considerably faster on average. For difficult random problems, that took between minutes and 1.5 hour to solve, MAC-3 d was about 1.5 times faster on average than MAC-2001. As soon as MAC-2001 starts to become successful in avoiding the duplication of many checks it begins to invest much more additional solution time. These observations suggest that being worst case optimal may come at a price of being less efficient on average in search and that algorithms like MAC-3 d are promising. Contents 1
Keyphrases
lightweight arc-consistency algorithm arc-consistency algorithm worst case optimal optimal worst case time-complexity clear winner mac search alone arc-consistency arc-consistency ac-3 worst case scenario worst case time-complexity single csp arc-consistent many check many backtrack algorithm additional solution time difficult random problem case scenario hand ac-2001 experimental evidence common belief
