Woodpusher

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|| [[image:Woodpusher.JPG width="210" height="224"]] ||~   || **Woodpusher**,
a chess program developed in 1989 by [[John Hamlen]] as part of a university project looking into [[Null Move|null-move]] search techniques. Woodpusher played various [[World Computer Chess Championship|World Computer-]], [[World Microcomputer Chess Championship|World Microcomputer Chess Championships]] and [[Computer Olympiad|Computer Olympiads]]. //Woodpusher 1997// played the [[WCCC 2004]] in [[http://en.wikipedia.org/wiki/Ramat_Gan|Ramat-Gan]] and the [[WCCC 2011]] in [[http://en.wikipedia.org/wiki/Tilburg|Tilburg]] as an experiment to play with a seven respectively fourteen years old program. ||
|| Woodpusher mascot  ||~   ||^   ||
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=Description= 
Description given in 1995 from the [[ICGA]] tournament site <ref>[[http://www.game-ai-forum.org/icga-tournaments/program.php?id=33|Woodpusher's ICGA Tournaments]]</ref> :
|| {{Woodpusher is a small chess program (< 64K) of conventional design. It uses an [[Iterative Deepening|iterative deepening]] [[Alpha-Beta|alpha-beta search]] with [[Principal Variation Search|PVS]] and [[Aspiration Windows|aspiration window]] enhancements. The first version of Woodpusher was born in 1989 as part of a university project looking into [[Null Move|null-move]] search techniques. True to it's origins, this new version of the program still uses the null-move throughout the search to recognize threats and to [[Pruning|forward prune]] branches of the [[Search Tree|search tree]]. A [[Attack and Defend Maps|database of attacks]] from and to all the squares on the board is maintained by using [[Chess (Program)|CHESS 4.5's]] [[Bitboards|bit-board]] implementation. These data structures are used for both [[Move Generation|generating moves]] and making positional [[Evaluation|evaluations]]. Woodpusher's position evaluation is maintained almost entirely [[Incremental Updates|incrementally]] while [[Make Move|making]] and [[Unmake Move|un-making]] moves during the search, with very little work done at the [[Terminal Node|terminal nodes]]. The evaluation is therefore necessarily simple, but does include true measures of [[Mobility|mobility]] rather than relying on [[Piece-Square Tables|piece-square evaluations]].}} ||

=Photos=
|| [[image:wccc2011-3.JPG]] ||
|| [[WCCC 2011]], [[Woodpusher|Woodpusher 1997]] by [[John Hamlen]] vs. [[Pandix]] by [[Gyula Horváth]] (left) <ref>Photos by [[Gerd Isenberg]]</ref> ||

=Namesakes= 
* [[http://mono-code.sourceforge.net/|WoodPusher]] a chess application written in [[C sharp|C#]] by [[http://sourceforge.net/projects/mono-code/|Jamin P. Gray]]

=See also=
* [[Knowledge#SearchVersusEvaluation|Knowledge | Search versus Evaluation]]
* [[Null Move Pruning]]
* [[Woodpecker]]

=Publications=
* [[John Hamlen]] (**2004**). //Seven Year Itch//. [[ICGA Journal]], Vol. 27, No. 4, pp. 255-258. <ref>[[http://en.wikipedia.org/wiki/Seven_Year_Itch_%28disambiguation%29|Seven Year Itch (disambiguation) from Wikipedia]]</ref> » [[WCCC 2004]]
* [[John Hamlen]] (**2012**). //Game Over for the Woodpusher Experiment: 7+7=0//. [[ICGA Journal]], Vol. 35, No. 1 » [[WCCC 2011]]

=Forum Posts=
* [[http://www.stmintz.com/ccc/index.php?id=376346|I think that woodpusher is the surprise of the tournament]] by [[Uri Blass]], [[CCC]], July 13, 2004 » [[WCCC 2004]]
* [[http://www.hiarcs.net/forums/viewtopic.php?p=2944|Re: Search or Evaluation?]] by [[Mark Uniacke]], [[Computer Chess Forums|Hiarcs Forum]], October 14, 2007 » [[Knowledge#SearchVersusEvaluation|Search versus Evaluation]], [[1st Computer Olympiad#Chess|1st Computer Olympiad]]

=External Links= 
* [[http://www.game-ai-forum.org/icga-tournaments/program.php?id=33|Woodpusher's ICGA Tournaments]]
* [[http://dictionary.reference.com/browse/woodpusher|Definition of Woodpusher at Dictionary.com]]

=References= 
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=What links here?= 
[[include page="Woodpusher" component="backlinks" limit="40" ]]
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