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'''[[Main Page|Home]] * [[Search]] * [[Selectivity]] * [[Reductions]] * Late Move Reductions'''
[[FILE:Bak_OtherRules.jpg|border|right|thumb|333px|link=http://chgs.elevator.umn.edu/asset/viewAsset/57f3b6787d58ae5f74bf8ba9#57f3b6d77d58ae5574bf8bc8|[[Arts#:Category:Samuel Bak|Samuel Bak]] - Other Rules <ref>[http://chgs.elevator.umn.edu/asset/viewAsset/57f3b6787d58ae5f74bf8ba9#57f3b6d77d58ae5574bf8bc8 Chess in the Art of Samuel Bak], [http://www.chgs.umn.edu/ Center for Holocaust & Genocide Studies], [https://en.wikipedia.org/wiki/University_of_Minnesota [University of Minnesota]]</ref> ]]
'''Late Move Reductions (LMR)''',<br/>
or its version known as '''History Pruning''' and '''History Reductions''' <ref>[http://members.home.nl/matador/hr.htm History Reductions in Pro Deo] by [[Ed Schroder|Ed Schröder]]</ref> , save search by reducing [[Moves|moves]] that are [[Move Ordering|ordered]] closer to the end of likely [[Node Types#ALL|fail-low nodes]]. Typically, most schemes search the first few moves (say 3-4) at full [[Depth|depth]], then if no move [[Fail-High|fails high]], many of the remaining moves are reduced in search [[Depth|depth]]. The technique has been used for many years in various forms, but it became very popular in 2005 after [[Fruit]] and [[Glaurung]] <ref>[https://web.archive.org/web/20150212051846/http://www.glaurungchess.com/lmr.html An Introduction to Late Move Reductions] by [[Tord Romstad]]([https://en.wikipedia.org/wiki/Wayback_Machine Wayback Machine])</ref> used open source implementations based on the [[History Heuristic]]. LMR can often reduce the [[Branching Factor#EffectiveBranchingFactor|effective branching factor]] to less than 2, depending on the reduction conditions.
=Common Conditions=
Most programs do not reduce these types of [[Moves|moves]]:
* [[Tactical movesMoves]] ([[Captures|captures]] and [[Promotions|promotions]])
* Moves while in [[Check|check]]
* Moves which give check
* Moves threatening the King area
* [[Tactics|Tactically]] threatening moves
* Moves with good past [[Relative History Heuristic|relative history]] <ref>[[Mark Winands]], [[Erik van der Werf]], [[Jaap van den Herik]], and [[Jos Uiterwijk]] ('''20062004'''). ''[http://link.springer.com/chapter/10.1007/11674399_18 The Relative History Heuristic]''. Computers and Games, Lecture Notes in Computer Science (LNCS 3846) (eds. [[Jaap van den HerikCG 2004]], [[Yngvi Björnsson]], and [[Nathan S. Netanyahu]]), pp. 262-272. [http://www.cserikvanderwerf.unimaastengen.nl/m.winands/documentspubdown/relhis.pdf pdf]</ref>
* Any [[Pawn Push|Pawn Moves]]
* Allowing reductions of "bad" [[Captures|captures]] ([[Static Exchange Evaluation|SEE]] < 0)
=Publications=
* [[David Levy]], [[David Broughton]], [[Mark Taylor]] ('''1989'''). ''The SEX Algorithm in Computer Chess''. [[ICGA Journal#12_1|ICCA Journal, Vol. 12, No. 1]]
* [[Kunihito Hoki]], [[Masakazu Muramatsu]] ('''2012'''). ''[https://www.semanticscholar.org/paper/Efficiency-of-three-forward-pruning-techniques-in-Hoki-Muramatsu/206099961f401c8693e071c2b739f164ae5ffa6c Efficiency of three Forward-Pruning Techniques in Shogi: Futility Pruning, Null-move Pruning, and Late Move Reduction (LMR)]''. [https://www.journals.elsevier.com/entertainment-computing Entertainment Computing], Vol. 3, No. 3
* [[Daniel Shawul|Daniel S. Abdi]] ('''2013'''). ''Analysis of pruned minimax trees''. [https://dl.dropboxusercontent.com/u/55295461/analysis/pruning.pdf pdf] » [[Alpha-Beta]], [[Null Move Pruning]]
* [http://www.talkchess.com/forum/viewtopic.php?t=65169 LMR and killer] by [[Harm Geert Muller]], [[CCC]], September 14, 2017 » [[Killer Heuristic]]
* [http://www.talkchess.com/forum/viewtopic.php?t=65273 LMR prescription] by [[Evert Glebbeek]], [[CCC]], September 24, 2017
'''2019'''
* [https://www.talkchess.com/forum3/viewtopic.php?f=7&t=70217 Depth reduced but ELO increased] by [[Tom King]], [[CCC]], March 16, 2019 » [[Playing Strength]]
==2020 ...==
* [https://www.talkchess.com/forum3/viewtopic.php?f=7&t=78397 Elo expected from LMR] by Christian Dean, [[CCC]], October 11, 2021 » [[Playing Strength]]
* [https://www.talkchess.com/forum3/viewtopic.php?f=7&t=79616 Troubles with LMR] by Kurt Peters, [[CCC]], March 31, 2022
=External Links=
* [https://en.wikipedia.org/wiki/Late_Move_Reductions Late Move Reductions from Wikipedia]
* [https://web.archive.org/web/20150212051846/http://www.glaurungchess.com/lmr.html An Introduction to Late Move Reductions] by [[Tord Romstad]] (dead link[https://en.wikipedia.org/wiki/Wayback_Machine Wayback Machine])* [http://mediocrechess.blogspot.de/2007/03/other-late-move-reduction-lmr.html Mediocre Chess: <nowiki>[Guide] </nowiki> Late move reduction (LMR)] by [[Jonatan Pettersson]], March 26, 2007 » [[Mediocre]]* [http://members.home.nl/matador/hr.htm History Reductions in Pro Deo] by [[Ed Schroder|Ed Schröder]] » [[Pro DeoProDeo]]
* [http://rebel13.nl/rebel13/blog/lmr%20advanced.html LMR advanced] from [http://rebel13.nl/index.html Rebel 13] by [[Ed Schroder]] <ref>[http://www.talkchess.com/forum/viewtopic.php?t=63870 LMR - or starters - Advance and Expert] by [[Ed Schroder]], [[CCC]], May 01, 2017</ref> » [[Rebel]]
=References=
<references />
'''[[Reductions|Up one level]]'''
[[Category:Samuel Bak]]
