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'''[[Main Page|Home]] * [[Search]] * Depth'''
[[FILE:EschersDepth.jpg|border|right|thumb|231px|link=http://www.mcescher.com/Gallery/recogn-bmp/LW403.jpg|[[Arts#:Category:M. C. Escher|M. C. Escher]], Depth, 1955 <ref>[http://www.mcescher.com/Gallery/gallery-recogn.htm Picture gallery "Recognition and Success 1955 - 1972"] from [http://www.mcescher.com/ The Official M.C. Escher Website]</ref>
]]
'''Depth''' is the height or ''nominal'' depth in [[Ply|plies]] between the [[Root|root]] and so called [[Horizon Node|horizon nodes]] (depth 0), where a heuristic value is assigned to. Thus, depth is the number of half moves the search ''nominally'' looks ahead.
Despite [[Quiescence Search|quiescence search]], where usually winning captures and even some checks are tried at or behind the search horizon, until positions become sufficiently quite, [[Selectivity|selectivity]] of modern chess programs, caused by [[Extensions|extensions]], [[Pruning|pruning]] and [[Reductions|reductions]], notably [[Check Extensions|check extensions]], [[Null Move Pruning|nNMPNMP]] and [[Late Move Reductions|LMR]], leads to bushy, non-uniform [[Search Tree|trees]] where some branches are searched deeper than nominal, but others shallower. A [[Depth Reduction R|depth reduction R]] of multiple plies is often performed in forward pruning techniques like [[Null Move Pruning|null move pruning]] and [[Multi-Cut|multi-cut]].
=Draft versus Ply-Index=
* [[Matej Guid]], [[Ivan Bratko]] ('''2007'''). ''Factors affecting diminishing returns for searching deeper''. [[ICGA Journal#30_2|ICGA Journal, Vol. 30, No. 2]], [http://www.ailab.si/matej/doc/Factors_Affecting_Diminishing_Returns.pdf pdf]
==2010 ...==
* [[Diogo R. Ferreira]] ('''2013'''). ''The Impact of the Search Depth on Chess Playing Strength''. [[ICGA Journal#36_2|ICGA Journal, Vol. 36, No. 2]]» [[#DiminishingReturns|Diminishing Returns]], [[Match Statistics]], [[Playing Strength]], [[Houdini]] <ref>[https://www.hiarcs.net/forums/viewtopic.php?t=10004 Ply versus ELO] by Greg, [[Computer Chess Forums|HIARCS Forum]], May 30, 2020 » [[Diogo R. Ferreira#Impact|Diogo R. Ferreira - Impact of the Search Depth ...]]</ref>
* [[Tamal T. Biswas]], [[Kenneth W. Regan]] ('''2015'''). ''Quantifying Depth and Complexity of Thinking and Knowledge''. [http://www.icaart.org/EuropeanProjectSpace.aspx?y=2015 ICAART 2015], [http://www.cse.buffalo.edu/~regan/papers/pdf/BiReICAART15CR.pdf pdf]
* [[Tamal T. Biswas]], [[Kenneth W. Regan]] ('''2015'''). ''Measuring Level-K Reasoning, Satisficing, and Human Error in Game-Play Data''. [[IEEE]] [http://www.icmla-conference.org/icmla15/ ICMLA 2015], [http://www.cse.buffalo.edu/~regan/papers/pdf/BiRe15_ICMLA2015.pdf pdf preprint]
* [[Matej Guid]], [[Ivan Bratko]] ('''2017'''). ''Influence of Search Depth on Position Evaluation''. [[Advances in Computer Games 15]]
=Forum PostsPostings= ==1983 ...==* [http://quux.org:70/Archives/usenet-a-news/NET.chess/82.01.07_alice.349_net.chess.txt chess strength] by [[Ken Thompson]], [http://quux.org:70/Archives/usenet-a-news/NET.chess net.chess], January 7, 1982
==1996 ...==
* [https://groups.google.com/d/msg/rec.games.chess.computer/1uVIWZFB41k/VUcAUkzyFd0J Fractional depth increments] by S. Read, [[Computer Chess Forums|rgcc]], January 18, 1996
==2010 ...==
* [http://www.open-chess.org/viewtopic.php?f=5&t=1403 Node counts at a given depth/iteration in search] by [[Mark Watkins|BB+]], [[Computer Chess Forums|OpenChess Forum]], May 23, 2011
* [http://www.talkchess.com/forum3/viewtopic.php?f=7&t=42677 Counting depth as a function of number of legal moves] by [[Pio Korinth]], [[CCC]], February 28, 2012
* [http://www.talkchess.com/forum/viewtopic.php?t=43134 Elo versus speed] by [[Peter Österlund]], [[CCC]], April 02, 2012
* [http://www.talkchess.com/forum/viewtopic.php?t=43596 From 5 ply to 6....] by [[Fernando Villegas]], [[CCC]], May 06, 2012
* [http://www.talkchess.com/forum/viewtopic.php?t=63326 Ridiculous QSearch Depth] by [[Jonathan Rosenthal]], [[CCC]], March 03, 2017 » [[Quiescence Search]]
* [http://www.talkchess.com/forum3/viewtopic.php?f=7&t=70217 Depth reduced but ELO increased] by [[Tom King]], [[CCC]], March 16, 2019 » [[Countermove Heuristic]], [[Playing Strength]]
==2020 ...==
* [https://www.hiarcs.net/forums/viewtopic.php?t=10004 Ply versus ELO] by Greg, [[Computer Chess Forums|HIARCS Forum]], May 30, 2020 » [[Diogo R. Ferreira#Impact|Diogo R. Ferreira - Impact of the Search Depth ...]]
=External Links=
