25,161
edits
Changes
Created page with "'''Home * Search * Selectivity * Extensions * Check Extensions''' '''Check Extensions''' have two distinct forms: one of them extends when giving ..."
'''[[Main Page|Home]] * [[Search]] * [[Selectivity]] * [[Extensions]] * Check Extensions'''
'''Check Extensions''' have two distinct forms: one of them extends when giving [[Check|check]], the other - when ''evading'' it. In each case, typical [[Depth|depth]] to extend is '''one''' ply. The reason behind check extension is that we are in a forcing sequence, so that it is desirable to know its outcome with more certainty, and the number of replies to check is limited, so we do not have to be afraid of a [[Search Explosion|search explosion]]. Also, not extending checks may easily lead to the [[Horizon Effect|horizon effect]], delaying the threat so far that the program cannot see it. However, some programmers don't extend checks (and captures) with negative [[Static Exchange Evaluation|SEE]] or even [[Reductions|reduce]] them. [[Robert Hyatt]] claimed a significant gain in [[Crafty]] by doing so <ref>[http://www.talkchess.com/forum/viewtopic.php?topic_view=threads&p=368875&t=35955 Re: move count based pruning] by [[Robert Hyatt]], [[CCC]], September 04, 2010</ref> <ref>[http://www.talkchess.com/forum/viewtopic.php?t=54281 search extensions] by [[Robert Hyatt]], [[CCC]], November 08, 2014</ref>.
If a program does not consider checks in the [[Quiescence Search|quiescence search]], then we should take care that it does not enter it while in check. This is also a form of check extension <ref>[http://www.talkchess.com/forum/viewtopic.php?t=23447 checks in q-search] by [[Robert Hyatt]], [[CCC]], September 02, 2008</ref>. In its most straightforward form, check extension is implemented in [[TSCP]].
=See also=
* [[Quiescence Search#Checks|Checks in Quiescence Search]]
* [[One Reply Extensions]]
* [[Singular Extensions]]
=Forum Posts=
==2000 ...==
* [https://www.stmintz.com/ccc/index.php?id=274620 Check Extension] by [[Martin Bauer]], [[CCC]], January 03, 2003
* [https://www.stmintz.com/ccc/index.php?id=289795 What's best low BF or good WAC result?] by [[Albert Bertilsson]], [[CCC]], March 18, 2003 » [[Win at Chess]]
* [https://www.stmintz.com/ccc/index.php?id=290060 Buggy check extensions, back to square one =(.] by [[Albert Bertilsson]], [[CCC]], March 20, 2003
* [https://www.stmintz.com/ccc/index.php?id=358170 check extention explosion] by Aivaras Juzvikas, [[CCC]], April 03, 2004 » [[Search Explosion]]
* [http://www.open-aurec.com/wbforum/viewtopic.php?f=4&t=702&p=2642 Checks in QSearch] by [[Dan Honeycutt]], [[Computer Chess Forums|Winboard Programming Forum]], November 23, 2004 » [[Quiescence Search#Checks|Checks in Quiescence Search]]
==2005 ...==
* [http://www.talkchess.com/forum/viewtopic.php?t=14075 hashing, check extensions and depth] by [[Mike Adams]], [[CCC]], May 27, 2007
* [http://www.talkchess.com/forum/viewtopic.php?t=14333 Revisiting Check Extensions] by [[Mark Lefler]], [[CCC]], June 07, 2007
* [http://www.talkchess.com/forum/viewtopic.php?t=23447 checks in q-search] by [[Robert Hyatt]], [[CCC]], September 02, 2008
* [http://www.talkchess.com/forum/viewtopic.php?t=22840 check extension] by [[Andrew Short]], [[CCC]], August 07, 2008
* [http://www.talkchess.com/forum/viewtopic.php?t=24614 check extensions] by [[Robert Hyatt]], [[CCC]], October 28, 2008
* [http://www.talkchess.com/forum/viewtopic.php?t=27384 Check extension] by [[Harm Geert Muller]], [[CCC]], April 09, 2009
==2010 ...==
* [http://www.talkchess.com/forum/viewtopic.php?t=31505 Problem with exploding tree because of extensions] by [[Oliver Brausch]], [[CCC]], January 05, 2010
* [http://talkchess.com/forum/viewtopic.php?t=32345 Problems when implementing checks in qsearch] by [[Luca Hemmerich]], [[CCC]], February 03, 2010 » [[Quiescence Search#Checks|Checks in Quiescence Search]]
* [http://www.talkchess.com/forum/viewtopic.php?t=52309 Spite checks] by [[Harm Geert Muller]], [[CCC]], May 13, 2014
* [http://www.talkchess.com/forum/viewtopic.php?t=53078 Pointless delays] by [[Harm Geert Muller]], [[CCC]], July 25, 2014
==2015 ...==
* [http://www.talkchess.com/forum/viewtopic.php?t=55874 Check-extension in QS] by [[Harm Geert Muller]], [[CCC]], April 03, 2015 » [[Quiescence Search#Checks|Checks in Quiescence Search]]
* [http://www.talkchess.com/forum/viewtopic.php?t=56361 Is a Check Extension Really a Win?] by [[Steve Maughan]], [[CCC]], May 15, 2015
* [http://www.talkchess.com/forum/viewtopic.php?t=61803 Spite checks, again] by [[Harm Geert Muller]], [[CCC]], October 23, 2016
* [http://www.talkchess.com/forum/viewtopic.php?t=63303 Starting with check extensions] by [[Luis Babboni]], [[CCC]], February 28, 2017
* [http://www.talkchess.com/forum/viewtopic.php?t=63319 Check Extensions] by [[David Cimbalista]], [[CCC]], March 02, 2017
* [http://www.talkchess.com/forum/viewtopic.php?t=63649 Check extension vs LMR] by [[Harm Geert Muller]], [[CCC]], April 04, 2017 » [[Late Move Reductions|LMR]]
* [http://www.talkchess.com/forum/viewtopic.php?t=67131 Depth extensions and effect on transposition queries] by [[Kenneth Jones]], [[CCC]], April 16, 2018 » [[Transposition Table]]
=External Links=
* Extension Techniques in REBEL (checks) from [http://www.top-5000.nl/authors/rebel/chess840.htm Programmer Corner] by [[Ed Schroder|Ed Schröder]]
* [http://web.archive.org/web/20070607151732/www.brucemo.com/compchess/programming/extensions.htm#check Check extension] from [[Bruce Moreland|Bruce Moreland's]] [http://web.archive.org/web/20070607231311/www.brucemo.com/compchess/programming/index.htm Programming Topics]
=References=
<references />
'''[[Extensions|Up one Level]]'''
'''Check Extensions''' have two distinct forms: one of them extends when giving [[Check|check]], the other - when ''evading'' it. In each case, typical [[Depth|depth]] to extend is '''one''' ply. The reason behind check extension is that we are in a forcing sequence, so that it is desirable to know its outcome with more certainty, and the number of replies to check is limited, so we do not have to be afraid of a [[Search Explosion|search explosion]]. Also, not extending checks may easily lead to the [[Horizon Effect|horizon effect]], delaying the threat so far that the program cannot see it. However, some programmers don't extend checks (and captures) with negative [[Static Exchange Evaluation|SEE]] or even [[Reductions|reduce]] them. [[Robert Hyatt]] claimed a significant gain in [[Crafty]] by doing so <ref>[http://www.talkchess.com/forum/viewtopic.php?topic_view=threads&p=368875&t=35955 Re: move count based pruning] by [[Robert Hyatt]], [[CCC]], September 04, 2010</ref> <ref>[http://www.talkchess.com/forum/viewtopic.php?t=54281 search extensions] by [[Robert Hyatt]], [[CCC]], November 08, 2014</ref>.
If a program does not consider checks in the [[Quiescence Search|quiescence search]], then we should take care that it does not enter it while in check. This is also a form of check extension <ref>[http://www.talkchess.com/forum/viewtopic.php?t=23447 checks in q-search] by [[Robert Hyatt]], [[CCC]], September 02, 2008</ref>. In its most straightforward form, check extension is implemented in [[TSCP]].
=See also=
* [[Quiescence Search#Checks|Checks in Quiescence Search]]
* [[One Reply Extensions]]
* [[Singular Extensions]]
=Forum Posts=
==2000 ...==
* [https://www.stmintz.com/ccc/index.php?id=274620 Check Extension] by [[Martin Bauer]], [[CCC]], January 03, 2003
* [https://www.stmintz.com/ccc/index.php?id=289795 What's best low BF or good WAC result?] by [[Albert Bertilsson]], [[CCC]], March 18, 2003 » [[Win at Chess]]
* [https://www.stmintz.com/ccc/index.php?id=290060 Buggy check extensions, back to square one =(.] by [[Albert Bertilsson]], [[CCC]], March 20, 2003
* [https://www.stmintz.com/ccc/index.php?id=358170 check extention explosion] by Aivaras Juzvikas, [[CCC]], April 03, 2004 » [[Search Explosion]]
* [http://www.open-aurec.com/wbforum/viewtopic.php?f=4&t=702&p=2642 Checks in QSearch] by [[Dan Honeycutt]], [[Computer Chess Forums|Winboard Programming Forum]], November 23, 2004 » [[Quiescence Search#Checks|Checks in Quiescence Search]]
==2005 ...==
* [http://www.talkchess.com/forum/viewtopic.php?t=14075 hashing, check extensions and depth] by [[Mike Adams]], [[CCC]], May 27, 2007
* [http://www.talkchess.com/forum/viewtopic.php?t=14333 Revisiting Check Extensions] by [[Mark Lefler]], [[CCC]], June 07, 2007
* [http://www.talkchess.com/forum/viewtopic.php?t=23447 checks in q-search] by [[Robert Hyatt]], [[CCC]], September 02, 2008
* [http://www.talkchess.com/forum/viewtopic.php?t=22840 check extension] by [[Andrew Short]], [[CCC]], August 07, 2008
* [http://www.talkchess.com/forum/viewtopic.php?t=24614 check extensions] by [[Robert Hyatt]], [[CCC]], October 28, 2008
* [http://www.talkchess.com/forum/viewtopic.php?t=27384 Check extension] by [[Harm Geert Muller]], [[CCC]], April 09, 2009
==2010 ...==
* [http://www.talkchess.com/forum/viewtopic.php?t=31505 Problem with exploding tree because of extensions] by [[Oliver Brausch]], [[CCC]], January 05, 2010
* [http://talkchess.com/forum/viewtopic.php?t=32345 Problems when implementing checks in qsearch] by [[Luca Hemmerich]], [[CCC]], February 03, 2010 » [[Quiescence Search#Checks|Checks in Quiescence Search]]
* [http://www.talkchess.com/forum/viewtopic.php?t=52309 Spite checks] by [[Harm Geert Muller]], [[CCC]], May 13, 2014
* [http://www.talkchess.com/forum/viewtopic.php?t=53078 Pointless delays] by [[Harm Geert Muller]], [[CCC]], July 25, 2014
==2015 ...==
* [http://www.talkchess.com/forum/viewtopic.php?t=55874 Check-extension in QS] by [[Harm Geert Muller]], [[CCC]], April 03, 2015 » [[Quiescence Search#Checks|Checks in Quiescence Search]]
* [http://www.talkchess.com/forum/viewtopic.php?t=56361 Is a Check Extension Really a Win?] by [[Steve Maughan]], [[CCC]], May 15, 2015
* [http://www.talkchess.com/forum/viewtopic.php?t=61803 Spite checks, again] by [[Harm Geert Muller]], [[CCC]], October 23, 2016
* [http://www.talkchess.com/forum/viewtopic.php?t=63303 Starting with check extensions] by [[Luis Babboni]], [[CCC]], February 28, 2017
* [http://www.talkchess.com/forum/viewtopic.php?t=63319 Check Extensions] by [[David Cimbalista]], [[CCC]], March 02, 2017
* [http://www.talkchess.com/forum/viewtopic.php?t=63649 Check extension vs LMR] by [[Harm Geert Muller]], [[CCC]], April 04, 2017 » [[Late Move Reductions|LMR]]
* [http://www.talkchess.com/forum/viewtopic.php?t=67131 Depth extensions and effect on transposition queries] by [[Kenneth Jones]], [[CCC]], April 16, 2018 » [[Transposition Table]]
=External Links=
* Extension Techniques in REBEL (checks) from [http://www.top-5000.nl/authors/rebel/chess840.htm Programmer Corner] by [[Ed Schroder|Ed Schröder]]
* [http://web.archive.org/web/20070607151732/www.brucemo.com/compchess/programming/extensions.htm#check Check extension] from [[Bruce Moreland|Bruce Moreland's]] [http://web.archive.org/web/20070607231311/www.brucemo.com/compchess/programming/index.htm Programming Topics]
=References=
<references />
'''[[Extensions|Up one Level]]'''
