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''see Main page: [[Shared Hash Table]]''
This technique is a very simple approach to [[SMP]]. The implementation requires little more than starting additional processors. Processors are simply fed the root position at the beginning of the search, and each searches the same tree with the only communication being the [[Transposition Table|transposition table]]. The gains come from the effect of nondeterminism. Each processor will finish the various subtrees in varying amounts of time, and as the search continues, these effects grow making the search trees diverge. The speedup is then based on how many nodes the main processor is able to skip from transposition table entries. Many programs used this if a "quick and dirty" approach to SMP is needed. It had the reputation of little speedup on a mere 2 processors, and to scale quite badly after this.
<span id="Lazy"></span>
==Lazy SMP==
=Taxonomy=
Overview and taxonomy of parallel algorithms based on [[Alpha-Beta|alpha-beta]], given by [[Mark Brockington]], [[ICGA Journal#19_3|ICCA Journal, Vol. 19: No. 3]] in 1996 <ref>[[Mark Brockington]] ('''1996'''). ''A Taxonomy of Parallel Game-Tree Search Algorithms''. [[ICGA Journal#19_3|ICCA Journal, Vol. 19: No. 3]]</ref> <ref>[https://www.talkchess.com/forum3/viewtopic.php?f=7&t=78631 Research paper comparing various parallel search algorithms] by koedem, [[CCC]], November 10, 2021</ref>
{| class="wikitable"
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'''1983'''
* [[Raphael Finkel]], [[John Philip Fishburn]] ('''1983'''). ''Improved Speedup Bounds for Parallel Alpha-Beta Search''. [[IEEE#TPAMI|IEEE Transactions on Pattern Analysis and Machine Intelligence]], Vol. 5, No. 1, pp. 89 - 92
* [[Clyde Kruskal]] ('''1983'''). ''[httphttps://ieeexplore.ieee.org/xpldocument/freeabs_all.jsp1676138?arnumber=1676138 Searching, Merging, and Sorting in Parallel Computation]''. [[IEEE#TOC|IEEE Transactions on Computers]], Vol. C-32, No 10
* [[Gary Lindstrom]] ('''1983'''). ''The Key Node Method: A Highly-Parallel Alpha-Beta Algorithm''. Technical Report UUCCS 83-101, [https://en.wikipedia.org/wiki/University_of_Utah University of Utah], [http://content.lib.utah.edu/utils/getfile/collection/uspace/id/3706/filename/image pdf]
'''1984'''
* [[Baruch Awerbuch]] ('''1985'''). ''[http://www.sciencedirect.com/science/article/pii/0020019085900833 A New Distributed Depth-First Search Algorithm]''. [https://en.wikipedia.org/wiki/Information_Processing_Letters Information Processing Letters], Vol. 20, No. 3
* [[Monroe Newborn]] ('''1985'''). ''A Parallel Search Chess Program''. Proceedings of the ACM Annual Conference, pp. 272-277. Denver, Co.
* [[Clyde Kruskal]], [https://en.wikipedia.org/wiki/Alan_Weiss_%28mathematician%29 [Mathematician#AWeiss|Alan Weiss]] ('''1985'''). ''Allocating Independent Subtasks on Parallel Processors''. [https://en.wikipedia.org/wiki/IEEE_Transactions_on_Software_Engineering [IEEE#SE|IEEE Transactions on Software Engineering]], Vol. 11, No. 10
* [http://www.informatik.uni-trier.de/~ley/pers/hd/l/Leifker:Daniel_B=.html Daniel B. Leifker], [[Laveen Kanal|Laveen N. Kanal]] ('''1985'''). ''[http://dl.acm.org/citation.cfm?id=1623687 A Hybrid SSS*/Alpha-Beta Algorithm for Parallel Search of Game Trees]''. [http://www.informatik.uni-trier.de/~ley/db/conf/ijcai/ijcai85.html#LeifkerK85 IJCAI'85] » [[SSS* and Dual*]]
'''1986'''
==1990 ...==
* [[Rainer Feldmann]], [[Peter Mysliwietz]], [[Burkhard Monien]] ('''1991''') ''A Fully Distributed Chess Program''. [[Advances in Computer Chess 6]], [http://www.top-5000.nl/ps/A%20fully%20distribuited%20chess%20program.pdf pdf]
* [[Clyde Kruskal]], [[Mathematician#LRudolph|Larry Rudolph]], [[Mathematician#MSnir|Marc Snir]] ('''1990'''). ''[https://www.sciencedirect.com/science/article/pii/030439759090192K A Complexity Theory of Efficient Parallel Algorithms]''. [https://en.wikipedia.org/wiki/Theoretical_Computer_Science_%28journal%29 Theoretical Computer Science], Vol. 71
* [[Clyde Kruskal]], [[Mathematician#LRudolph|Larry Rudolph]], [[Mathematician#MSnir|Marc Snir]] ('''1990'''). ''[https://link.springer.com/article/10.1007/BF01840376 Efficient Parallel Algorithms for Graph Problems]''. [https://en.wikipedia.org/wiki/Algorithmica Algorithmica], Vol. 5, No. 1
'''1992'''
* [[Jaleh Rezaie]], [[Raphael Finkel]] ('''1992'''). ''[https://www.researchgate.net/publication/2813087_A_comparison_of_some_parallel_game-tree_search_algorithms_Revised_version A comparison of some parallel game-tree search algorithms]''. [https://en.wikipedia.org/wiki/University_of_Kentucky University of Kentucky]
* [http://www.talkchess.com/forum/viewtopic.php?t=48612 use sleeping threads] by [[Don Dailey]], [[CCC]], July 10, 2013 » [[Stockfish]]
* [http://www.talkchess.com/forum/viewtopic.php?t=48752 Recursive DTS-like search algorithm] by [[Peter Österlund]], [[CCC]], July 24, 2013 » [[Texel]], [[Recursion]]
* [http://www.open-chess.org/viewtopic.php?f=5&t=2378 DTS-like SMP] by [[Vadim Demichev|ThinkingALot]], [[Computer Chess Forums|OpenChess Forum]], July 25, 2013 » [[Gull]]
* [http://www.talkchess.com/forum/viewtopic.php?t=48780 Time to depth measuring tool] by [[Peter Österlund]], [[CCC]], July 28, 2013 » [[Depth]]
* [http://www.talkchess.com/forum/viewtopic.php?t=49450 interesting SMP bug] by [[Robert Hyatt]], [[CCC]], September 24, 2013 » [[Crafty]]
* [http://www.talkchess.com/forum3/viewtopic.php?f=7&t=71115 OpenMP for chess programming] by BeyondCritics, [[CCC]], June 27, 2019
* [http://www.talkchess.com/forum3/viewtopic.php?f=7&t=71739 Multithreaded noob question] by [[Michael Sherwin]], [[CCC]], September 06, 2019
==2020 ...==
* [https://www.talkchess.com/forum3/viewtopic.php?f=7&t=75695 assembler for locking at AMD magny cours] by [[Vincent Diepeveen]], [[CCC]], November 06, 2020
* [https://www.talkchess.com/forum3/viewtopic.php?f=7&t=78631 Research paper comparing various parallel search algorithms] by koedem, [[CCC]], November 10, 2021
=External Links=
