Difference between revisions of "Hash Move"

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(Created page with "'''Home * Chess * Moves * Hash Move''' ''The '''Hash Move''' is a Move Ordering related issue.'' The '''Hash Move''' is a move probed from the Tr...")
 
 
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''The '''Hash Move''' is a [[Move Ordering]] related issue.''
 
''The '''Hash Move''' is a [[Move Ordering]] related issue.''
  
The '''Hash Move''' is a move probed from the [[Transposition Table|transposition table]], either a [[Best Move|best move]] of a stored [[Node Types#PV|PV-node]] - a [[PV-move]], or a good enough [[Refutation Move|refutation move]] to cause a [[Beta-Cutoff|cutoff]]. This move should most importantly searched first <ref>but usually after trying the [[Null Move]] of the [[Null Move Pruning|Null Move Heuristic]]</ref> <ref> [http://www.talkchess.com/forum/viewtopic.php?t=64093 tt move vs null move] by [[Erin Dame]], [[CCC]], May 27, 2017</ref>. One may save the [[Move Generation|move generation]] at all, if the hash move actually [[Fail-High|fails high]]. To guard against rare  [[Transposition Table#KeyCollisions|TT key collisions]], one may apply a [[Legal Move|legality test]] of the hash move <ref>[[Robert Hyatt]], [[Anthony Cozzie]] ('''2005'''). ''[http://www.cis.uab.edu/hyatt/collisions.html The Effect of Hash Signature Collisions in a Chess Program]''. [[ICGA Journal|ICGA Journal, Vol. 28., No. 3]]</ref>.
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The '''Hash Move''' is a move probed from the [[Transposition Table|transposition table]], either a [[Best Move|best move]] of a stored [[Node Types#PV|PV-node]] - a [[PV-Move|PV-move]], or a good enough [[Refutation Move|refutation move]] to cause a [[Beta-Cutoff|cutoff]]. This move should most importantly searched first <ref>but usually after trying the [[Null Move]] of the [[Null Move Pruning|Null Move Heuristic]]</ref> <ref> [http://www.talkchess.com/forum/viewtopic.php?t=64093 tt move vs null move] by [[Erin Dame]], [[CCC]], May 27, 2017</ref>. One may save the [[Move Generation|move generation]] at all, if the hash move actually [[Fail-High|fails high]]. To guard against rare  [[Transposition Table#KeyCollisions|TT key collisions]], one may apply a [[Legal Move|legality test]] of the hash move <ref>[[Robert Hyatt]], [[Anthony Cozzie]] ('''2005'''). ''[http://www.cis.uab.edu/hyatt/collisions.html The Effect of Hash Signature Collisions in a Chess Program]''. [[ICGA Journal|ICGA Journal, Vol. 28., No. 3]]</ref>.
  
 
=See also=
 
=See also=

Latest revision as of 10:00, 11 October 2019

Home * Chess * Moves * Hash Move

The Hash Move is a Move Ordering related issue.

The Hash Move is a move probed from the transposition table, either a best move of a stored PV-node - a PV-move, or a good enough refutation move to cause a cutoff. This move should most importantly searched first [1] [2]. One may save the move generation at all, if the hash move actually fails high. To guard against rare TT key collisions, one may apply a legality test of the hash move [3].

See also

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