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Created page with "'''Home * Search * Quiescence''' border|right|thumb|link=http://www.yogachicago.com/jan06/art.shtml|[[Arts#Schuman|Karen Schuman, Qu..."
'''[[Main Page|Home]] * [[Search]] * Quiescence'''
[[FILE:Quiescence.jpg|border|right|thumb|link=http://www.yogachicago.com/jan06/art.shtml|[[Arts#Schuman|Karen Schuman]], Quiescence <ref>Quiescence by [[Arts#Schuman|Karen Schuman]] from [http://www.yogachicago.com/jan06/art.shtml Artist Karen Schuman’s Personal Mythology] Reviewed by [http://www.chicagoartcriticsassociation.org/B/poplawska.html Anna Poplawska]</ref> ]]
Most chess programs, at the end of the main search perform a more limited '''quiescence''' search, containing fewer moves. The purpose of this search is to only [[Evaluation|evaluate]] "quiet" [[Chess Position|positions]], or positions where there are no winning [[Tactical Moves|tactical moves]] to be made. This search is needed to avoid the [[Horizon Effect|horizon effect]]. Simply stopping your search when you reach the desired [[Depth|depth]] and then evaluate, is very dangerous. Consider the situation where the last move you consider is QxP. If you stop there and evaluate, you might think that you have won a pawn. But what if you were to search one move deeper and find that the next move is PxQ? You didn't win a pawn, you actually lost a queen. Hence the need to make sure that you are evaluating only quiescent (quiet) positions.
=Limiting Quiescence<span id="Limiting Quiescence"></span>=
Despite the fact that quiescence searches are typically very short, about 50%-90% nodes are spent there, so it is worthwhile to apply some [[Pruning|pruning]] there. Apart from not trying moves with the [[Static Exchange Evaluation|static exchange evaluation]] < 0, [[Delta Pruning|delta pruning]] can be used for that purpose.
<span id="StandPat"></span>
=Standing Pat=
In order to allow the quiescence search to stabilize, we need to be able to stop searching without necessarily searching all available [[Captures|captures]]. In addition, we need a score to return in case there are no captures available to be played. This is done by a using the [[Evaluation|static evaluation]] as a "stand-pat" score (the term is taken from the game of poker, where it denotes playing one's hand without drawing more cards). At the beginning of quiescence, the position's evaluation is used to establish a [[Lower Bound|lower bound]] on the score. This is theoretically sound because we can usually assume that there is at least one move that can either match or beat the lower bound. This is based on the [[Null Move Observation]] - it assumes that we are not in [[Zugzwang]]. If the lower bound from the stand pat score is already greater than or equal to beta, we can return the stand pat score ([[Fail-Soft|fail-soft]]) or [[Beta|beta]] ([[Fail-Hard|fail-hard]]) as a [[Lower Bound|lower bound]]. Otherwise, the search continues, keeping the evaluated "stand-pat" score as an [[Lower Bound|lower bound]] if it exceeds [[Alpha|alpha]], to see if any [[Tactical moves|tactical moves]] can increase [[Alpha|alpha]].
<span id="Checks"></span>
=Checks=
Some programs search treat [[Check|checks]] and check evasions specially in quiescence. The idea behind this is that if the side to move is in check, the position is not quiet, and there is a threat that needs to be resolved. In this case, all evasions to the check are searched. Stand pat is not allowed if we are in check, for two reasons. First, because we are not sure that there is a move that can match alpha--in many positions a check can mean a serious threat that cannot be resolved. Second, because we are searching every move in the position, rather than only [[Captures|captures]].
Standing pat assumes that even if we finish searching all moves, and none of them increase alpha, one of the non-tactical moves can most likely raise alpha. This is not valid if we search every move. The other case of treating checks specially is the checking moves themselves. Some programs, after searching all the captures in a position without finding a move to raise alpha, will generate non-capture moves that give check. This has to be limited somehow, however, because in most given positions there will be very many long and pointless checking sequences that do not amount to anything. Most programs achieve this limit by delta pruning checks, as well as limiting the generation of checks to the first X plies of quiescence.
=Pseudo Code=
<pre>
int Quiesce( int alpha, int beta ) {
int stand_pat = Evaluate();
if( stand_pat >= beta )
return beta;
if( alpha < stand_pat )
alpha = stand_pat;
until( every_capture_has_been_examined ) {
MakeCapture();
score = -Quiesce( -beta, -alpha );
TakeBackMove();
if( score >= beta )
return beta;
if( score > alpha )
alpha = score;
}
return alpha;
}
</pre>
=See also=
* [[Bobby#StrategicQuiescenceSearch|Bobby's Strategic Quiescence Search]]
* [[CPW-Engine_quiescence]]
* [[Null Move Pruning#NMQS|Don Beal's Generalized Quiescence Search]]
* [[Horizon Effect#Crossovers|Crossovers]]
* [[Delta Pruning]]
* [[Horizon Effect]]
* [[Horizon Node]]
* [[MVV-LVA]]
* [[Quiescent Node]]
* [[Search Explosion]]
* [[Static Exchange Evaluation]]
* [[SOMA#Swapoff|Swap-off algorithm - SOMA]]
* [[Helmut Richter#Swapoff|Swap-off]] by [[Helmut Richter]]
* [[Vice#Quiescence|Vice Video on Quiescence]]
* [[Zzzzzz#Quiescence|Zzzzzz' Quiescence Search]]
=Publications=
==1975==
* [[Larry Harris]] ('''1975''') ''The Heuristic Search And The Game Of Chess - A Study Of Quiescence, Sacrifices, And Plan Oriented Play''. [http://www.informatik.uni-trier.de/%7Eley/db/conf/ijcai/index.html IJCAI] 1975 Tbilisi, Georgia: 334-339. reprinted ('''1988''') in [[Computer Chess Compendium]]
==1980 ...==
* [[Hermann Kaindl]] ('''1982'''). ''Dynamic Control of the Quiescence Search in Computer Chess''. Cybernetics and Systems Research (ed. R. Trappl), pp. 973-977. North-Holland, Amsterdam.
* [[Hermann Kaindl]] ('''1982'''). ''Quiescence Search in Computer Chess.'' SIGART Newsletter, 80, pp. 124-131. Reprinted (1983) in Computer-Game-Playing: Theory and Practice, pp. 39-52. Ellis Horwood Ltd., Chichester.
* [[Don Beal]] ('''1984'''). ''Mating Sequences in the Quiescence Search''. [[ICGA Journal#7_3|ICCA Journal, Vol. 7, No. 3]]
* [[Prakash Bettadapur]] ('''1986'''). ''Experiments in Chess Capture Search'', M.Sc. Thesis, Department of Computing Science, [[University of Alberta]].
* [[Prakash Bettadapur]] ('''1986'''). ''Influence of Ordering on Capture Search''. [[ICGA Journal#9_4|ICCA Journal, Vol. 9, No. 4]]
* [[Prakash Bettadapur]], [[Tony Marsland]] ('''1988'''). ''Accuracy and Savings in Depth-Limited Capture Search''. In [http://www.informatik.uni-trier.de/%7Eley/db/journals/ijmms/ijmms29.html#BettadapurM88 International Journal of Man-Machine Studies, 29] (5) pp. 497-502
* [[Don Beal]] ('''1989'''). ''Experiments with the Null Move.'' [[Advances in Computer Chess 5]], a revised version is published ('''1990''') under the title ''A Generalized Quiescence Search Algorithm''. [https://en.wikipedia.org/wiki/Artificial_Intelligence_%28journal%29 Artificial Intelligence], Vol. 43, No. 1, pp. 85-98. ISSN 0004-3702, edited version in ('''1999'''). ''The Nature of MINIMAX Search''. Ph.D. thesis, IKAT, ISBN 90-62-16-6348. Chapter 10, pp. 101-116 » [[Null Move]]
* [[Günther Schrüfer]] ('''1989'''). ''A Strategic Quiescence Search''. [[ICGA Journal#12_1|ICCA Journal, Vol. 12, No. 1]] » [[Bobby#StrategicQuiescenceSearch|Bobby's Strategic Quiescence Search]]
==1990 ...==
* [[Don Beal]] ('''1990'''). ''A Generalized Quiescence Search Algorithm''. [https://en.wikipedia.org/wiki/Artificial_Intelligence_%28journal%29 Artificial Intelligence], Vol. 43, No. 1, pp. 85-98. ISSN 0004-3702
* [[Sören Walter Perrey]] ('''1991'''). ''Mathematische Methoden der Künstlichen Intelligenz: Zur Quiescence-Suche in Spielbäumen''. Diplom thesis, Sonderforschungsbereich 343, [http://www.mathematik.uni-bielefeld.de/sfb343/preprints/index91.html E91-006], [https://en.wikipedia.org/wiki/Bielefeld_University University of Bielefeld] (German) <ref>[[Ingo Althöfer]] ('''1991'''). ''Mathematische Methoden der Künstlichen Intelligenz: Zur Quiescence-Suche in Spielbäumen''. Review, [[ICGA Journal#14_2|ICCA Journal, Vol. 14, No. 2]]</ref>
* [[Michael Gherrity]], [[Mathematician#PKube|Paul Kube]] ('''1993'''). ''Quiescent Search is Beneficial.'' Technical Report CS93-289, [http://de.wikipedia.org/wiki/University_of_California,_San_Diego University of California, San Diego]
* [[Don Beal]] ('''1999'''). ''The Nature of MINIMAX Search''. Ph.D. thesis, IKAT, ISBN 90-62-16-6348
==2000 ...==
* [[Jeff Rollason]] ('''2000'''). ''SUPER-SOMA - Solving Tactical Exchanges in Shogi without Tree Searching''. [https://en.wikipedia.org/wiki/Lecture_Notes_in_Computer_Science Lecture Notes In Computer Science], Vol. 2063, [[CG 2000]], [http://www.aifactory.co.uk/downloads/SUPER-SOMA.doc Word preprint] <ref>[[Jeff Rollason]] ('''2006'''). ''[http://www.aifactory.co.uk/newsletter/2006_03_quiescence_alts.htm Looking for Alternatives to Quiescence Search]''. [[AI Factory]], Autumn 2006</ref>
* [[Jeff Rollason]] ('''2006'''). ''[http://www.aifactory.co.uk/newsletter/2006_03_quiescence_alts.htm Looking for Alternatives to Quiescence Search]''. [[AI Factory]], Autumn 2006
* [[Don Beal]] ('''2006'''). ''[[File:alg1986review.txt|Review of a nullmove-quiescence search mechanism from 1986]]''. (Draft) <ref>courtesy of [[Don Beal]] and [[Carey Bloodworth]], [http://www.talkchess.com/forum/viewtopic.php?t=58603&start=13 Re: Antique chess programs] by [[Carey Bloodworth|Carey]], [[CCC]], December 16, 2015</ref>
* [[Maarten Schadd]], [[Mark Winands]] ('''2009'''). ''Quiescence Search for Stratego''. In BNAIC 2009, [http://www.personeel.unimaas.nl/Maarten-Schadd/Papers/2009StrategoBNAIC1.pdf pdf]
=Forum Posts=
==1994 ...==
* [http://groups.google.com/group/rec.games.chess/browse_frm/thread/ee86982df38f003c Efficient quiescence] by [[Hans Bogaards]], [[Computer Chess Forums|rec.games.chess]], January 19, 1994
* [http://groups.google.com/group/rec.games.chess/browse_frm/thread/dd1c55ecc9f48717 Computer Chess: swap down evaluators vs capture search] by [[Jon Dart]], [[Computer Chess Forums|rgc]], October 24, 1994 » [[SOMA#Swapoff|Swap-off algorithm - SOMA]]
: [http://groups.google.com/group/rec.games.chess/msg/527be476c5dd22d1 Re: Computer Chess: swap down evaluators vs capture search] by [[Deniz Yuret]], [[Computer Chess Forums|rgc]], October 26, 1994
* [http://groups.google.com/group/rec.games.chess.computer/browse_frm/thread/a027ac0e2fb5892e quiescence search problems] by [[Matt Craighead]], [[Computer Chess Forums|rgcc]], August 01, 1995
: [https://groups.google.com/group/rec.games.chess.computer/msg/fedfcfaf26d04dfa Re: Quiescence search problems] by [[David Blackman]], [[Computer Chess Forums|rgcc]], August 3, 1995 » [[Integrated Bounds and Values]]
* [http://groups.google.com/group/rec.games.chess.computer/browse_frm/thread/926eaf0869b6f176 quiescent vs non-quiescent node counting] by [[Robert Hyatt]], [[Computer Chess Forums|rgcc]], July 01, 1996
* [http://groups.google.com/group/rec.games.chess.computer/browse_frm/thread/6fb02db95638ade1 Deep Quiesence Searching] by Steve Dicks, [[Computer Chess Forums|rgcc]], February 22, 1997
* [https://groups.google.com/group/rec.games.chess.computer/browse_frm/thread/ca0300b50438a388 quiescence search] by [[Andrew Tridgell]], [[Computer Chess Forums|rgcc]], April 16, 1997 » [[Check]], [[Crafty]]
* [https://www.stmintz.com/ccc/index.php?id=13485 Limiting the QSearch] by John Scalo, [[CCC]], December, 30, 1997
* [https://www.stmintz.com/ccc/index.php?id=17016 Quiescence vs swapoff] by [[Peter Fendrich]], [[CCC]], April 15, 1998
* [https://www.stmintz.com/ccc/index.php?id=63511 SEE for forward pruning in Q. Search] by [[Tom King]], [[CCC]], August 04, 1999 » [[Static Exchange Evaluation|SEE]]
* [https://www.stmintz.com/ccc/index.php?id=64357 SEE for forward pruning in the Q. search - I'm confused!] by [[Tom King]], [[CCC]], August 11, 1999
==2000 ...==
* [https://www.stmintz.com/ccc/index.php?id=86662 What is the q-search?] by [[Leonid Liberman|Leonid]], [[CCC]], January 07, 2000
* [https://www.stmintz.com/ccc/index.php?id=141230 Qsearch problems...(about sorting and SEE)] by [[Severi Salminen]], [[CCC]], November 26, 2000 » [[Static Exchange Evaluation]]
'''2001'''
* [https://www.stmintz.com/ccc/index.php?id=148445 Bonus points for side to move in qsearch?] by [[Leen Ammeraal]], [[CCC]], January 06, 2001 » [[Tempo]]
* [https://www.stmintz.com/ccc/index.php?id=204243 About limiting Qsearch, again...] by [[Severi Salminen]], [[CCC]], December 29, 2001
* [https://www.stmintz.com/ccc/index.php?id=203771 About qsearch...] by [[Severi Salminen]], [[CCC]], December 27, 2001
* [https://www.stmintz.com/ccc/index.php?id=204492 Qsearch survey] by [[Severi Salminen]], [[CCC]], December 30, 2001
'''2002'''
* [https://www.stmintz.com/ccc/index.php?id=237893 Checks in the Qsearch] by [[Scott Gasch]], [[CCC]], June 28, 2002 » [[Check]]
* [https://www.stmintz.com/ccc/index.php?id=260485 A question about quiescence search] by Nagendra Singh Tomar, [[CCC]], October 19, 2002
* [https://www.stmintz.com/ccc/index.php?id=267486 Quiescence Explosion] by [[David Rasmussen]], [[CCC]], November 26, 2002
* [https://www.stmintz.com/ccc/index.php?id=303257 Quiescent Explosion] by macaroni, [[CCC]], June 26, 2003
* [https://www.stmintz.com/ccc/index.php?id=310897 Regarding Qsearch with Fractional ply extensions] by [[Federico Andrés Corigliano|Federico Corigliano]], [[CCC]], August 11, 2003 » [[Depth#FractionalPlies|Depth - Fractional Plies]]
* [https://www.stmintz.com/ccc/index.php?id=313206 real job of the qSearch? find quiet vs stop horizon effect] by [[Scott Farrell]], [[CCC]], August 28, 2003
* [http://groups.google.com/group/rec.games.chess.computer/browse_frm/thread/d451877add19a50e quiescence] by Noah Roberts, [[Computer Chess Forums|rgcc]], September 20, 2003
'''2004'''
* [https://www.stmintz.com/ccc/index.php?id=342287 QSearch() as PVS() ?] by [[Matthias Gemuh]], [[CCC]], January 14, 2004
* [https://www.stmintz.com/ccc/index.php?id=344282 Rebel's long checks concept in QS] by [[Anastasios Milikas|milix]], [[CCC]], January 23, 2004 » [[Rebel]], [[Check]]
* [https://www.stmintz.com/ccc/index.php?id=344566 quiesce node explosion] by Mike Siler, [[CCC]], January 24, 2004
* [https://www.stmintz.com/ccc/index.php?id=385027 Qsearch Checks] by [[Tor Lattimore]], [[CCC]], August 29, 2004 » [[Check]]
* [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
==2005 ...==
* [https://www.stmintz.com/ccc/index.php?id=445400 quiescence search / horizon question] by [[Andrew Shapira]], [[CCC]], August 26, 2005
* [http://www.talkchess.com/forum/viewtopic.php?p=139285 How to Best Limit Checks in the Quiescence ?] by [[Stuart Cracraft]], [[CCC]], August 20, 2007 » [[Check]], [[Quiescence Search#Checks|Checks in Quiescence Search]]
* [http://www.talkchess.com/forum/viewtopic.php?t=20727 Quiescence Search Explosions] by [[Mike Leany]], [[CCC]], April 18, 2008
* [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=28023 Limiting Quiescent Search Depth] by [[John Merlino]], [[CCC]], May 20, 2009
* [http://www.talkchess.com/forum/viewtopic.php?t=29439 Null move in quiescence search idea from Don Beal, 1986] by [[Eelco de Groot]], [[CCC]], Aug 17, 2009 » [[Null Move Pruning]], [[Don Beal]]
* [http://www.talkchess.com/forum/viewtopic.php?p=291259 Threat information from evaluation to inform q-search] by [[Gary Linscott|Gary]], [[CCC]], September 15, 2009
* [http://www.talkchess.com/forum/viewtopic.php?t=30738 Only recaptures in qsearch?] by [[John Merlino]], [[CCC]], November 21, 2009
==2010 ...==
* [http://www.talkchess.com/forum/viewtopic.php?t=32148 Avoiding qsearch explosion] by [[Marco Costalba]], [[CCC]], January 29, 2010
* [http://talkchess.com/forum/viewtopic.php?t=32345 Problems when implementing checks in qsearch] by [[Luca Hemmerich]], [[CCC]], February 03, 2010
* [http://www.talkchess.com/forum/viewtopic.php?t=32424 Standpat and check] by [[Vlad Stamate]], [[CCC]], February 06, 2010 » [[Quiescence Search#StandPat|Standing Pat]], [[Check]]
* [http://www.talkchess.com/forum/viewtopic.php?t=36692 This is totally weird ... Don't understand at all] by [[Gregory Strong]], [[CCC]], November 13, 2010
'''2012'''
* [http://www.talkchess.com/forum/viewtopic.php?t=42971 checks in quies] by [[Larry Kaufman]], [[CCC]], March 22, 2012
* [http://www.talkchess.com/forum/viewtopic.php?t=42982 stand pat or side to move bonus] by [[Larry Kaufman]], [[CCC]], March 22, 2012
* [http://www.talkchess.com/forum/viewtopic.php?t=44507 Some thoughts on QS] by [[Harm Geert Muller]], [[CCC]], July 19, 2012
* [http://www.talkchess.com/forum/viewtopic.php?t=44599 QSearch, checks and the lack of progress...] by [[Mincho Georgiev]], [[CCC]], July 27, 2012
* [http://www.talkchess.com/forum/viewtopic.php?t=45942 Quiescence - Check Evaluation and Depth Control] by [[Cheney Nattress]], [[CCC]], November 10, 2012
'''2013'''
* [http://www.talkchess.com/forum/viewtopic.php?t=47162 Quiescent search, and side to move is in check] by [[Louis Zulli]], [[CCC]], February 08, 2013
* [http://www.talkchess.com/forum/viewtopic.php?t=47373 Transposition table usage in quiescent search?] by [[Jerry Donald]], [[CCC]], March 01, 2013 » [[Transposition Table]]
* [http://www.talkchess.com/forum/viewtopic.php?t=47423 Pruning in QS] by [[Harm Geert Muller]], [[CCC]], March 06, 2013 » [[Pruning]]
* [http://www.talkchess.com/forum/viewtopic.php?t=47436 QS investigation] by [[Ed Schroder|Ed Schröder]], [[CCC]], March 07, 2013
* [http://www.open-chess.org/viewtopic.php?f=5&t=2402 qsearch question] by nak3c, [[Computer Chess Forums|OpenChess Forum]], August 19, 2013
* [http://www.talkchess.com/forum/viewtopic.php?t=49311 about qs] by [[Daniel Anulliero]], [[CCC]], September 11, 2013
'''2014'''
* [http://www.talkchess.com/forum/viewtopic.php?t=51967 Positional quiesence] by [[Harm Geert Muller]], [[CCC]], April 12, 2014
* [http://www.talkchess.com/forum/viewtopic.php?t=54755 Transposition table in Q-search] by [[Alex Ferguson]], [[CCC]], December 26, 2014 » [[Transposition Table]]
==2015 ...==
* [http://www.talkchess.com/forum/viewtopic.php?t=55424 Detail evaluation within quiescence search] by [[Reinhard Scharnagl]], [[CCC]], February 22, 2015
* [http://www.talkchess.com/forum/viewtopic.php?t=55427 hanging piece at starting quiescence search - how to handle?] by [[Reinhard Scharnagl]], [[CCC]], February 22, 2015 » [[Hanging Piece]]
* [http://www.talkchess.com/forum/viewtopic.php?t=55474 Search algorithm in it's simplest forum] by [[Mahmoud Uthman]], [[CCC]], February 25, 2015 » [[Alpha-Beta]]
* [http://www.talkchess.com/forum/viewtopic.php?t=55874 Check-extension in QS] by [[Harm Geert Muller]], [[CCC]], April 03, 2015 » [[Check]]
* [http://www.open-chess.org/viewtopic.php?f=5&t=2852 quiescence search (best practices)] by thevinenator, [[Computer Chess Forums|OpenChess Forum]], July 02, 2015
* [http://www.talkchess.com/forum/viewtopic.php?t=58527 Null Move in Quiescent search] by [[Laurie Tunnicliffe]], [[CCC]], December 09, 2015 » [[Null Move Pruning]], [[Search Pathology]]
'''2016'''
* [http://www.talkchess.com/forum/viewtopic.php?t=59529 Checks in qsearch - must-have or optional?] by [[Martin Fierz]], [[CCC]], March 15, 2016 » [[Check]], [[Quiescence Search#Checks|Checks in Quiescence Search]]
* [http://talkchess.com/forum/viewtopic.php?t=59740 Hashing in Qsearch?] by [[Martin Fierz]], [[CCC]], April 03, 2016 » [[Transposition Table]]
* [http://www.open-chess.org/viewtopic.php?f=5&t=2984 Quiescence node explosion] by [[Sander Maassen vd Brink|sandermvdb]], [[Computer Chess Forums|OpenChess Forum]], June 01, 2016 » [[Search Explosion]]
* [http://www.talkchess.com/forum/viewtopic.php?t=60962 Starting with quiescence search] by [[Luis Babboni]], [[CCC]], July 28, 2016
* [http://www.talkchess.com/forum/viewtopic.php?t=60964 Quiescence Search Performance] by [[David Cimbalista]], [[CCC]], July 28, 2016
* [http://www.talkchess.com/forum/viewtopic.php?t=61307 Removing Q-search] by [[Matthew Lai]], [[CCC]], September 02, 2016
* [http://www.talkchess.com/forum/viewtopic.php?t=61348 Searching using slow eval with tactical verification] by [[Matthew Lai]], [[CCC]], September 06, 2016
* [http://www.talkchess.com/forum/viewtopic.php?t=61796 Collecting PVs of Qsearch ?] by [[Mahmoud Uthman]], [[CCC]], October 22, 2016 » [[Principal Variation]], [[Triangular PV-Table]]
'''2017'''
* [http://www.open-chess.org/viewtopic.php?f=5&t=3072 capturing PV in QSearch] by thevinenator, [[Computer Chess Forums|OpenChess Forum]], January 20, 2017 » [[Principal Variation]], [[Triangular PV-Table]]
* [http://www.talkchess.com/forum/viewtopic.php?t=63326 Ridiculous QSearch Depth] by [[Jonathan Rosenthal]], [[CCC]], March 03, 2017 » [[Depth]]
* [http://www.talkchess.com/forum/viewtopic.php?t=63590 Q search explosion] by [[Colin Jenkins]], [[CCC]], March 30, 2017 » [[Search Explosion]]
* [http://www.talkchess.com/forum/viewtopic.php?t=64030 Probe EGT in quiescence?] by [[Pham Hong Nguyen|Nguyen Pham]], [[CCC]], May 20, 2017 » [[Endgame Tablebases]], [[Chinese Chess|Xiangqi]]
* [http://www.talkchess.com/forum/viewtopic.php?t=64674 Is expensive eval required for QS?] by [[Alexandru Mosoi]], [[CCC]], July 21, 2017 » [[Lazy Evaluation]]
=External Links=
* [https://en.wikipedia.org/wiki/Quiescence_search Quiescence search from Wikipedia]
* [https://en.wikipedia.org/wiki/Quiescence Quiescence from Wikipedia]
* [http://web.archive.org/web/20070813042640/www.seanet.com/~brucemo/topics/quiescent.htm Quiescence Search] from [[Bruce Moreland|Bruce Moreland's]] [http://web.archive.org/web/20070811182741/www.seanet.com/%7Ebrucemo/topics/topics.htm Programming Topics]
* [http://www.top-5000.nl/authors/rebel/chess840.htm#QS Quiescent Search in REBEL ] from [[Ed Schroder|Ed Schröder's]] [http://www.top-5000.nl/authors/rebel/chess840.htm Programmer Stuff]
* [https://en.wikipedia.org/wiki/Pim_Jacobs Pim Jacobs], [http://nl.wikipedia.org/wiki/Ruud_Jacobs Ruud Jacobs], [http://nl.wikipedia.org/wiki/Ruud_Brink Ruud Brink], [https://en.wikipedia.org/wiki/Wim_Overgaauw Wim Overgaauw], [[Videos#DomUmRomao|Dom Um Romão]], [https://en.wikipedia.org/wiki/Astrud_Gilberto Astrud Gilberto] - [https://en.wikipedia.org/wiki/Meditation_%28song%29 Meditation], [https://en.wikipedia.org/wiki/It_Might_as_Well_Be_Spring It Might as Well Be Spring], Telephone Song, [https://en.wikipedia.org/wiki/Only_Trust_Your_Heart Only Trust Your Heart], [https://en.wikipedia.org/wiki/Corcovado_%28song%29 Corcovado (Quiet Nights of Quiet Stars)], [https://en.wikipedia.org/wiki/The_Girl_from_Ipanema The Girl From Ipanema]; from [http://www.cultura.nl/genres/kunst/2014/brazili-.html Dzjes Zien à la Bossa Nova], [https://en.wikipedia.org/wiki/Nederlandse_Christelijke_Radio_Vereniging NCRV] 1965, [https://en.wikipedia.org/wiki/YouTube YouTube] Video
: {{#evu:https://www.youtube.com/watch?v=9DCaxN6TfH4|alignment=left|valignment=top}}
=References=
<references />
'''[[Search|Up one level]]'''
[[FILE:Quiescence.jpg|border|right|thumb|link=http://www.yogachicago.com/jan06/art.shtml|[[Arts#Schuman|Karen Schuman]], Quiescence <ref>Quiescence by [[Arts#Schuman|Karen Schuman]] from [http://www.yogachicago.com/jan06/art.shtml Artist Karen Schuman’s Personal Mythology] Reviewed by [http://www.chicagoartcriticsassociation.org/B/poplawska.html Anna Poplawska]</ref> ]]
Most chess programs, at the end of the main search perform a more limited '''quiescence''' search, containing fewer moves. The purpose of this search is to only [[Evaluation|evaluate]] "quiet" [[Chess Position|positions]], or positions where there are no winning [[Tactical Moves|tactical moves]] to be made. This search is needed to avoid the [[Horizon Effect|horizon effect]]. Simply stopping your search when you reach the desired [[Depth|depth]] and then evaluate, is very dangerous. Consider the situation where the last move you consider is QxP. If you stop there and evaluate, you might think that you have won a pawn. But what if you were to search one move deeper and find that the next move is PxQ? You didn't win a pawn, you actually lost a queen. Hence the need to make sure that you are evaluating only quiescent (quiet) positions.
=Limiting Quiescence<span id="Limiting Quiescence"></span>=
Despite the fact that quiescence searches are typically very short, about 50%-90% nodes are spent there, so it is worthwhile to apply some [[Pruning|pruning]] there. Apart from not trying moves with the [[Static Exchange Evaluation|static exchange evaluation]] < 0, [[Delta Pruning|delta pruning]] can be used for that purpose.
<span id="StandPat"></span>
=Standing Pat=
In order to allow the quiescence search to stabilize, we need to be able to stop searching without necessarily searching all available [[Captures|captures]]. In addition, we need a score to return in case there are no captures available to be played. This is done by a using the [[Evaluation|static evaluation]] as a "stand-pat" score (the term is taken from the game of poker, where it denotes playing one's hand without drawing more cards). At the beginning of quiescence, the position's evaluation is used to establish a [[Lower Bound|lower bound]] on the score. This is theoretically sound because we can usually assume that there is at least one move that can either match or beat the lower bound. This is based on the [[Null Move Observation]] - it assumes that we are not in [[Zugzwang]]. If the lower bound from the stand pat score is already greater than or equal to beta, we can return the stand pat score ([[Fail-Soft|fail-soft]]) or [[Beta|beta]] ([[Fail-Hard|fail-hard]]) as a [[Lower Bound|lower bound]]. Otherwise, the search continues, keeping the evaluated "stand-pat" score as an [[Lower Bound|lower bound]] if it exceeds [[Alpha|alpha]], to see if any [[Tactical moves|tactical moves]] can increase [[Alpha|alpha]].
<span id="Checks"></span>
=Checks=
Some programs search treat [[Check|checks]] and check evasions specially in quiescence. The idea behind this is that if the side to move is in check, the position is not quiet, and there is a threat that needs to be resolved. In this case, all evasions to the check are searched. Stand pat is not allowed if we are in check, for two reasons. First, because we are not sure that there is a move that can match alpha--in many positions a check can mean a serious threat that cannot be resolved. Second, because we are searching every move in the position, rather than only [[Captures|captures]].
Standing pat assumes that even if we finish searching all moves, and none of them increase alpha, one of the non-tactical moves can most likely raise alpha. This is not valid if we search every move. The other case of treating checks specially is the checking moves themselves. Some programs, after searching all the captures in a position without finding a move to raise alpha, will generate non-capture moves that give check. This has to be limited somehow, however, because in most given positions there will be very many long and pointless checking sequences that do not amount to anything. Most programs achieve this limit by delta pruning checks, as well as limiting the generation of checks to the first X plies of quiescence.
=Pseudo Code=
<pre>
int Quiesce( int alpha, int beta ) {
int stand_pat = Evaluate();
if( stand_pat >= beta )
return beta;
if( alpha < stand_pat )
alpha = stand_pat;
until( every_capture_has_been_examined ) {
MakeCapture();
score = -Quiesce( -beta, -alpha );
TakeBackMove();
if( score >= beta )
return beta;
if( score > alpha )
alpha = score;
}
return alpha;
}
</pre>
=See also=
* [[Bobby#StrategicQuiescenceSearch|Bobby's Strategic Quiescence Search]]
* [[CPW-Engine_quiescence]]
* [[Null Move Pruning#NMQS|Don Beal's Generalized Quiescence Search]]
* [[Horizon Effect#Crossovers|Crossovers]]
* [[Delta Pruning]]
* [[Horizon Effect]]
* [[Horizon Node]]
* [[MVV-LVA]]
* [[Quiescent Node]]
* [[Search Explosion]]
* [[Static Exchange Evaluation]]
* [[SOMA#Swapoff|Swap-off algorithm - SOMA]]
* [[Helmut Richter#Swapoff|Swap-off]] by [[Helmut Richter]]
* [[Vice#Quiescence|Vice Video on Quiescence]]
* [[Zzzzzz#Quiescence|Zzzzzz' Quiescence Search]]
=Publications=
==1975==
* [[Larry Harris]] ('''1975''') ''The Heuristic Search And The Game Of Chess - A Study Of Quiescence, Sacrifices, And Plan Oriented Play''. [http://www.informatik.uni-trier.de/%7Eley/db/conf/ijcai/index.html IJCAI] 1975 Tbilisi, Georgia: 334-339. reprinted ('''1988''') in [[Computer Chess Compendium]]
==1980 ...==
* [[Hermann Kaindl]] ('''1982'''). ''Dynamic Control of the Quiescence Search in Computer Chess''. Cybernetics and Systems Research (ed. R. Trappl), pp. 973-977. North-Holland, Amsterdam.
* [[Hermann Kaindl]] ('''1982'''). ''Quiescence Search in Computer Chess.'' SIGART Newsletter, 80, pp. 124-131. Reprinted (1983) in Computer-Game-Playing: Theory and Practice, pp. 39-52. Ellis Horwood Ltd., Chichester.
* [[Don Beal]] ('''1984'''). ''Mating Sequences in the Quiescence Search''. [[ICGA Journal#7_3|ICCA Journal, Vol. 7, No. 3]]
* [[Prakash Bettadapur]] ('''1986'''). ''Experiments in Chess Capture Search'', M.Sc. Thesis, Department of Computing Science, [[University of Alberta]].
* [[Prakash Bettadapur]] ('''1986'''). ''Influence of Ordering on Capture Search''. [[ICGA Journal#9_4|ICCA Journal, Vol. 9, No. 4]]
* [[Prakash Bettadapur]], [[Tony Marsland]] ('''1988'''). ''Accuracy and Savings in Depth-Limited Capture Search''. In [http://www.informatik.uni-trier.de/%7Eley/db/journals/ijmms/ijmms29.html#BettadapurM88 International Journal of Man-Machine Studies, 29] (5) pp. 497-502
* [[Don Beal]] ('''1989'''). ''Experiments with the Null Move.'' [[Advances in Computer Chess 5]], a revised version is published ('''1990''') under the title ''A Generalized Quiescence Search Algorithm''. [https://en.wikipedia.org/wiki/Artificial_Intelligence_%28journal%29 Artificial Intelligence], Vol. 43, No. 1, pp. 85-98. ISSN 0004-3702, edited version in ('''1999'''). ''The Nature of MINIMAX Search''. Ph.D. thesis, IKAT, ISBN 90-62-16-6348. Chapter 10, pp. 101-116 » [[Null Move]]
* [[Günther Schrüfer]] ('''1989'''). ''A Strategic Quiescence Search''. [[ICGA Journal#12_1|ICCA Journal, Vol. 12, No. 1]] » [[Bobby#StrategicQuiescenceSearch|Bobby's Strategic Quiescence Search]]
==1990 ...==
* [[Don Beal]] ('''1990'''). ''A Generalized Quiescence Search Algorithm''. [https://en.wikipedia.org/wiki/Artificial_Intelligence_%28journal%29 Artificial Intelligence], Vol. 43, No. 1, pp. 85-98. ISSN 0004-3702
* [[Sören Walter Perrey]] ('''1991'''). ''Mathematische Methoden der Künstlichen Intelligenz: Zur Quiescence-Suche in Spielbäumen''. Diplom thesis, Sonderforschungsbereich 343, [http://www.mathematik.uni-bielefeld.de/sfb343/preprints/index91.html E91-006], [https://en.wikipedia.org/wiki/Bielefeld_University University of Bielefeld] (German) <ref>[[Ingo Althöfer]] ('''1991'''). ''Mathematische Methoden der Künstlichen Intelligenz: Zur Quiescence-Suche in Spielbäumen''. Review, [[ICGA Journal#14_2|ICCA Journal, Vol. 14, No. 2]]</ref>
* [[Michael Gherrity]], [[Mathematician#PKube|Paul Kube]] ('''1993'''). ''Quiescent Search is Beneficial.'' Technical Report CS93-289, [http://de.wikipedia.org/wiki/University_of_California,_San_Diego University of California, San Diego]
* [[Don Beal]] ('''1999'''). ''The Nature of MINIMAX Search''. Ph.D. thesis, IKAT, ISBN 90-62-16-6348
==2000 ...==
* [[Jeff Rollason]] ('''2000'''). ''SUPER-SOMA - Solving Tactical Exchanges in Shogi without Tree Searching''. [https://en.wikipedia.org/wiki/Lecture_Notes_in_Computer_Science Lecture Notes In Computer Science], Vol. 2063, [[CG 2000]], [http://www.aifactory.co.uk/downloads/SUPER-SOMA.doc Word preprint] <ref>[[Jeff Rollason]] ('''2006'''). ''[http://www.aifactory.co.uk/newsletter/2006_03_quiescence_alts.htm Looking for Alternatives to Quiescence Search]''. [[AI Factory]], Autumn 2006</ref>
* [[Jeff Rollason]] ('''2006'''). ''[http://www.aifactory.co.uk/newsletter/2006_03_quiescence_alts.htm Looking for Alternatives to Quiescence Search]''. [[AI Factory]], Autumn 2006
* [[Don Beal]] ('''2006'''). ''[[File:alg1986review.txt|Review of a nullmove-quiescence search mechanism from 1986]]''. (Draft) <ref>courtesy of [[Don Beal]] and [[Carey Bloodworth]], [http://www.talkchess.com/forum/viewtopic.php?t=58603&start=13 Re: Antique chess programs] by [[Carey Bloodworth|Carey]], [[CCC]], December 16, 2015</ref>
* [[Maarten Schadd]], [[Mark Winands]] ('''2009'''). ''Quiescence Search for Stratego''. In BNAIC 2009, [http://www.personeel.unimaas.nl/Maarten-Schadd/Papers/2009StrategoBNAIC1.pdf pdf]
=Forum Posts=
==1994 ...==
* [http://groups.google.com/group/rec.games.chess/browse_frm/thread/ee86982df38f003c Efficient quiescence] by [[Hans Bogaards]], [[Computer Chess Forums|rec.games.chess]], January 19, 1994
* [http://groups.google.com/group/rec.games.chess/browse_frm/thread/dd1c55ecc9f48717 Computer Chess: swap down evaluators vs capture search] by [[Jon Dart]], [[Computer Chess Forums|rgc]], October 24, 1994 » [[SOMA#Swapoff|Swap-off algorithm - SOMA]]
: [http://groups.google.com/group/rec.games.chess/msg/527be476c5dd22d1 Re: Computer Chess: swap down evaluators vs capture search] by [[Deniz Yuret]], [[Computer Chess Forums|rgc]], October 26, 1994
* [http://groups.google.com/group/rec.games.chess.computer/browse_frm/thread/a027ac0e2fb5892e quiescence search problems] by [[Matt Craighead]], [[Computer Chess Forums|rgcc]], August 01, 1995
: [https://groups.google.com/group/rec.games.chess.computer/msg/fedfcfaf26d04dfa Re: Quiescence search problems] by [[David Blackman]], [[Computer Chess Forums|rgcc]], August 3, 1995 » [[Integrated Bounds and Values]]
* [http://groups.google.com/group/rec.games.chess.computer/browse_frm/thread/926eaf0869b6f176 quiescent vs non-quiescent node counting] by [[Robert Hyatt]], [[Computer Chess Forums|rgcc]], July 01, 1996
* [http://groups.google.com/group/rec.games.chess.computer/browse_frm/thread/6fb02db95638ade1 Deep Quiesence Searching] by Steve Dicks, [[Computer Chess Forums|rgcc]], February 22, 1997
* [https://groups.google.com/group/rec.games.chess.computer/browse_frm/thread/ca0300b50438a388 quiescence search] by [[Andrew Tridgell]], [[Computer Chess Forums|rgcc]], April 16, 1997 » [[Check]], [[Crafty]]
* [https://www.stmintz.com/ccc/index.php?id=13485 Limiting the QSearch] by John Scalo, [[CCC]], December, 30, 1997
* [https://www.stmintz.com/ccc/index.php?id=17016 Quiescence vs swapoff] by [[Peter Fendrich]], [[CCC]], April 15, 1998
* [https://www.stmintz.com/ccc/index.php?id=63511 SEE for forward pruning in Q. Search] by [[Tom King]], [[CCC]], August 04, 1999 » [[Static Exchange Evaluation|SEE]]
* [https://www.stmintz.com/ccc/index.php?id=64357 SEE for forward pruning in the Q. search - I'm confused!] by [[Tom King]], [[CCC]], August 11, 1999
==2000 ...==
* [https://www.stmintz.com/ccc/index.php?id=86662 What is the q-search?] by [[Leonid Liberman|Leonid]], [[CCC]], January 07, 2000
* [https://www.stmintz.com/ccc/index.php?id=141230 Qsearch problems...(about sorting and SEE)] by [[Severi Salminen]], [[CCC]], November 26, 2000 » [[Static Exchange Evaluation]]
'''2001'''
* [https://www.stmintz.com/ccc/index.php?id=148445 Bonus points for side to move in qsearch?] by [[Leen Ammeraal]], [[CCC]], January 06, 2001 » [[Tempo]]
* [https://www.stmintz.com/ccc/index.php?id=204243 About limiting Qsearch, again...] by [[Severi Salminen]], [[CCC]], December 29, 2001
* [https://www.stmintz.com/ccc/index.php?id=203771 About qsearch...] by [[Severi Salminen]], [[CCC]], December 27, 2001
* [https://www.stmintz.com/ccc/index.php?id=204492 Qsearch survey] by [[Severi Salminen]], [[CCC]], December 30, 2001
'''2002'''
* [https://www.stmintz.com/ccc/index.php?id=237893 Checks in the Qsearch] by [[Scott Gasch]], [[CCC]], June 28, 2002 » [[Check]]
* [https://www.stmintz.com/ccc/index.php?id=260485 A question about quiescence search] by Nagendra Singh Tomar, [[CCC]], October 19, 2002
* [https://www.stmintz.com/ccc/index.php?id=267486 Quiescence Explosion] by [[David Rasmussen]], [[CCC]], November 26, 2002
* [https://www.stmintz.com/ccc/index.php?id=303257 Quiescent Explosion] by macaroni, [[CCC]], June 26, 2003
* [https://www.stmintz.com/ccc/index.php?id=310897 Regarding Qsearch with Fractional ply extensions] by [[Federico Andrés Corigliano|Federico Corigliano]], [[CCC]], August 11, 2003 » [[Depth#FractionalPlies|Depth - Fractional Plies]]
* [https://www.stmintz.com/ccc/index.php?id=313206 real job of the qSearch? find quiet vs stop horizon effect] by [[Scott Farrell]], [[CCC]], August 28, 2003
* [http://groups.google.com/group/rec.games.chess.computer/browse_frm/thread/d451877add19a50e quiescence] by Noah Roberts, [[Computer Chess Forums|rgcc]], September 20, 2003
'''2004'''
* [https://www.stmintz.com/ccc/index.php?id=342287 QSearch() as PVS() ?] by [[Matthias Gemuh]], [[CCC]], January 14, 2004
* [https://www.stmintz.com/ccc/index.php?id=344282 Rebel's long checks concept in QS] by [[Anastasios Milikas|milix]], [[CCC]], January 23, 2004 » [[Rebel]], [[Check]]
* [https://www.stmintz.com/ccc/index.php?id=344566 quiesce node explosion] by Mike Siler, [[CCC]], January 24, 2004
* [https://www.stmintz.com/ccc/index.php?id=385027 Qsearch Checks] by [[Tor Lattimore]], [[CCC]], August 29, 2004 » [[Check]]
* [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
==2005 ...==
* [https://www.stmintz.com/ccc/index.php?id=445400 quiescence search / horizon question] by [[Andrew Shapira]], [[CCC]], August 26, 2005
* [http://www.talkchess.com/forum/viewtopic.php?p=139285 How to Best Limit Checks in the Quiescence ?] by [[Stuart Cracraft]], [[CCC]], August 20, 2007 » [[Check]], [[Quiescence Search#Checks|Checks in Quiescence Search]]
* [http://www.talkchess.com/forum/viewtopic.php?t=20727 Quiescence Search Explosions] by [[Mike Leany]], [[CCC]], April 18, 2008
* [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=28023 Limiting Quiescent Search Depth] by [[John Merlino]], [[CCC]], May 20, 2009
* [http://www.talkchess.com/forum/viewtopic.php?t=29439 Null move in quiescence search idea from Don Beal, 1986] by [[Eelco de Groot]], [[CCC]], Aug 17, 2009 » [[Null Move Pruning]], [[Don Beal]]
* [http://www.talkchess.com/forum/viewtopic.php?p=291259 Threat information from evaluation to inform q-search] by [[Gary Linscott|Gary]], [[CCC]], September 15, 2009
* [http://www.talkchess.com/forum/viewtopic.php?t=30738 Only recaptures in qsearch?] by [[John Merlino]], [[CCC]], November 21, 2009
==2010 ...==
* [http://www.talkchess.com/forum/viewtopic.php?t=32148 Avoiding qsearch explosion] by [[Marco Costalba]], [[CCC]], January 29, 2010
* [http://talkchess.com/forum/viewtopic.php?t=32345 Problems when implementing checks in qsearch] by [[Luca Hemmerich]], [[CCC]], February 03, 2010
* [http://www.talkchess.com/forum/viewtopic.php?t=32424 Standpat and check] by [[Vlad Stamate]], [[CCC]], February 06, 2010 » [[Quiescence Search#StandPat|Standing Pat]], [[Check]]
* [http://www.talkchess.com/forum/viewtopic.php?t=36692 This is totally weird ... Don't understand at all] by [[Gregory Strong]], [[CCC]], November 13, 2010
'''2012'''
* [http://www.talkchess.com/forum/viewtopic.php?t=42971 checks in quies] by [[Larry Kaufman]], [[CCC]], March 22, 2012
* [http://www.talkchess.com/forum/viewtopic.php?t=42982 stand pat or side to move bonus] by [[Larry Kaufman]], [[CCC]], March 22, 2012
* [http://www.talkchess.com/forum/viewtopic.php?t=44507 Some thoughts on QS] by [[Harm Geert Muller]], [[CCC]], July 19, 2012
* [http://www.talkchess.com/forum/viewtopic.php?t=44599 QSearch, checks and the lack of progress...] by [[Mincho Georgiev]], [[CCC]], July 27, 2012
* [http://www.talkchess.com/forum/viewtopic.php?t=45942 Quiescence - Check Evaluation and Depth Control] by [[Cheney Nattress]], [[CCC]], November 10, 2012
'''2013'''
* [http://www.talkchess.com/forum/viewtopic.php?t=47162 Quiescent search, and side to move is in check] by [[Louis Zulli]], [[CCC]], February 08, 2013
* [http://www.talkchess.com/forum/viewtopic.php?t=47373 Transposition table usage in quiescent search?] by [[Jerry Donald]], [[CCC]], March 01, 2013 » [[Transposition Table]]
* [http://www.talkchess.com/forum/viewtopic.php?t=47423 Pruning in QS] by [[Harm Geert Muller]], [[CCC]], March 06, 2013 » [[Pruning]]
* [http://www.talkchess.com/forum/viewtopic.php?t=47436 QS investigation] by [[Ed Schroder|Ed Schröder]], [[CCC]], March 07, 2013
* [http://www.open-chess.org/viewtopic.php?f=5&t=2402 qsearch question] by nak3c, [[Computer Chess Forums|OpenChess Forum]], August 19, 2013
* [http://www.talkchess.com/forum/viewtopic.php?t=49311 about qs] by [[Daniel Anulliero]], [[CCC]], September 11, 2013
'''2014'''
* [http://www.talkchess.com/forum/viewtopic.php?t=51967 Positional quiesence] by [[Harm Geert Muller]], [[CCC]], April 12, 2014
* [http://www.talkchess.com/forum/viewtopic.php?t=54755 Transposition table in Q-search] by [[Alex Ferguson]], [[CCC]], December 26, 2014 » [[Transposition Table]]
==2015 ...==
* [http://www.talkchess.com/forum/viewtopic.php?t=55424 Detail evaluation within quiescence search] by [[Reinhard Scharnagl]], [[CCC]], February 22, 2015
* [http://www.talkchess.com/forum/viewtopic.php?t=55427 hanging piece at starting quiescence search - how to handle?] by [[Reinhard Scharnagl]], [[CCC]], February 22, 2015 » [[Hanging Piece]]
* [http://www.talkchess.com/forum/viewtopic.php?t=55474 Search algorithm in it's simplest forum] by [[Mahmoud Uthman]], [[CCC]], February 25, 2015 » [[Alpha-Beta]]
* [http://www.talkchess.com/forum/viewtopic.php?t=55874 Check-extension in QS] by [[Harm Geert Muller]], [[CCC]], April 03, 2015 » [[Check]]
* [http://www.open-chess.org/viewtopic.php?f=5&t=2852 quiescence search (best practices)] by thevinenator, [[Computer Chess Forums|OpenChess Forum]], July 02, 2015
* [http://www.talkchess.com/forum/viewtopic.php?t=58527 Null Move in Quiescent search] by [[Laurie Tunnicliffe]], [[CCC]], December 09, 2015 » [[Null Move Pruning]], [[Search Pathology]]
'''2016'''
* [http://www.talkchess.com/forum/viewtopic.php?t=59529 Checks in qsearch - must-have or optional?] by [[Martin Fierz]], [[CCC]], March 15, 2016 » [[Check]], [[Quiescence Search#Checks|Checks in Quiescence Search]]
* [http://talkchess.com/forum/viewtopic.php?t=59740 Hashing in Qsearch?] by [[Martin Fierz]], [[CCC]], April 03, 2016 » [[Transposition Table]]
* [http://www.open-chess.org/viewtopic.php?f=5&t=2984 Quiescence node explosion] by [[Sander Maassen vd Brink|sandermvdb]], [[Computer Chess Forums|OpenChess Forum]], June 01, 2016 » [[Search Explosion]]
* [http://www.talkchess.com/forum/viewtopic.php?t=60962 Starting with quiescence search] by [[Luis Babboni]], [[CCC]], July 28, 2016
* [http://www.talkchess.com/forum/viewtopic.php?t=60964 Quiescence Search Performance] by [[David Cimbalista]], [[CCC]], July 28, 2016
* [http://www.talkchess.com/forum/viewtopic.php?t=61307 Removing Q-search] by [[Matthew Lai]], [[CCC]], September 02, 2016
* [http://www.talkchess.com/forum/viewtopic.php?t=61348 Searching using slow eval with tactical verification] by [[Matthew Lai]], [[CCC]], September 06, 2016
* [http://www.talkchess.com/forum/viewtopic.php?t=61796 Collecting PVs of Qsearch ?] by [[Mahmoud Uthman]], [[CCC]], October 22, 2016 » [[Principal Variation]], [[Triangular PV-Table]]
'''2017'''
* [http://www.open-chess.org/viewtopic.php?f=5&t=3072 capturing PV in QSearch] by thevinenator, [[Computer Chess Forums|OpenChess Forum]], January 20, 2017 » [[Principal Variation]], [[Triangular PV-Table]]
* [http://www.talkchess.com/forum/viewtopic.php?t=63326 Ridiculous QSearch Depth] by [[Jonathan Rosenthal]], [[CCC]], March 03, 2017 » [[Depth]]
* [http://www.talkchess.com/forum/viewtopic.php?t=63590 Q search explosion] by [[Colin Jenkins]], [[CCC]], March 30, 2017 » [[Search Explosion]]
* [http://www.talkchess.com/forum/viewtopic.php?t=64030 Probe EGT in quiescence?] by [[Pham Hong Nguyen|Nguyen Pham]], [[CCC]], May 20, 2017 » [[Endgame Tablebases]], [[Chinese Chess|Xiangqi]]
* [http://www.talkchess.com/forum/viewtopic.php?t=64674 Is expensive eval required for QS?] by [[Alexandru Mosoi]], [[CCC]], July 21, 2017 » [[Lazy Evaluation]]
=External Links=
* [https://en.wikipedia.org/wiki/Quiescence_search Quiescence search from Wikipedia]
* [https://en.wikipedia.org/wiki/Quiescence Quiescence from Wikipedia]
* [http://web.archive.org/web/20070813042640/www.seanet.com/~brucemo/topics/quiescent.htm Quiescence Search] from [[Bruce Moreland|Bruce Moreland's]] [http://web.archive.org/web/20070811182741/www.seanet.com/%7Ebrucemo/topics/topics.htm Programming Topics]
* [http://www.top-5000.nl/authors/rebel/chess840.htm#QS Quiescent Search in REBEL ] from [[Ed Schroder|Ed Schröder's]] [http://www.top-5000.nl/authors/rebel/chess840.htm Programmer Stuff]
* [https://en.wikipedia.org/wiki/Pim_Jacobs Pim Jacobs], [http://nl.wikipedia.org/wiki/Ruud_Jacobs Ruud Jacobs], [http://nl.wikipedia.org/wiki/Ruud_Brink Ruud Brink], [https://en.wikipedia.org/wiki/Wim_Overgaauw Wim Overgaauw], [[Videos#DomUmRomao|Dom Um Romão]], [https://en.wikipedia.org/wiki/Astrud_Gilberto Astrud Gilberto] - [https://en.wikipedia.org/wiki/Meditation_%28song%29 Meditation], [https://en.wikipedia.org/wiki/It_Might_as_Well_Be_Spring It Might as Well Be Spring], Telephone Song, [https://en.wikipedia.org/wiki/Only_Trust_Your_Heart Only Trust Your Heart], [https://en.wikipedia.org/wiki/Corcovado_%28song%29 Corcovado (Quiet Nights of Quiet Stars)], [https://en.wikipedia.org/wiki/The_Girl_from_Ipanema The Girl From Ipanema]; from [http://www.cultura.nl/genres/kunst/2014/brazili-.html Dzjes Zien à la Bossa Nova], [https://en.wikipedia.org/wiki/Nederlandse_Christelijke_Radio_Vereniging NCRV] 1965, [https://en.wikipedia.org/wiki/YouTube YouTube] Video
: {{#evu:https://www.youtube.com/watch?v=9DCaxN6TfH4|alignment=left|valignment=top}}
=References=
<references />
'''[[Search|Up one level]]'''
