SOMA

the //**S**mith **O**ne-**M**ove **A**nalyzer//, a chess program designed as one-ply analyzing "paper machine" by [|evolutionary biologist] John Maynard Smith in the early 60s as a challenger to Machiavelli, of whose method of working he was in ignorance. Similar to their predecessors from the late 40s, Turochamp by Alan Turing and David Champernowne, and Machiavelli by Donald Michie and Shaun Wylie, SOMA looks one ply ahead, to do a static evaluation of all leaf-positions to choose the move which maximizes the evaluation score, considering material, center- and neighboring king square control. Since there was no quiescence search, swap-off values were used to determine own and opponent pieces en prise, and to modify the evaluation score accordantly. || toc =Features= John Maynard Smith's and Donald Michie's description of SOMA's evaluation features and weights from their 1961 paper //Machines that play games//, excerpt : 
 * Home * Engines * SOMA**
 * [[image:soma.JPG width="366" height="218" link="http://en.wikipedia.org/wiki/Perikaryon"]] ||~  || **SOMA**,
 * Structure of a typical [|neuron] ||~  ||^   ||

Material

 * (i) ||

Square Control

 * (ii) ||

Swap-off Value

 * (iii)

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Misc


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=SOMA - Machiavelli= Following game between SOMA and Machiavelli was played, with the conclusion that it seems unlikely that a one-ply analyzer would beat any but the most inexperienced human player. code [Event "?"] [Site "?"] [Date "1961.??.??"] [Round "?"] [White "SOMA"] [Black "Machiavelli"] [Result "1/2-1/2"]

1.e3 e5 2.d4 Nc6 3.Nc3 d5 4.Nf3 e4 5.Ne5 Bb4 6.Nxc6 bxc6 7.Bd2 Nf6 8.a3 Bd6 9.h4 Bg4 10.Be2 Qd7 11.O-O O-O-O 12.f3 Bf5 13.fxe4 Bxe4 14.Ba6+ Kb8 15.Nxe4 Nxe4 16.Qe2 Qe6 17.Ba5 Ng3 18.Qf3 Nxf1 19.Rxf1 f6 20.Rd1 Qe4 21.Qxe4 dxe4 22.d5 cxd5 23.Rxd5 {diagram} Be5 24.Rb5+ Ka8 25.Bb7+ Kb8 26.Bxe4+ Kc8 27.Bf5+ Rd7 28.Bxd7+ Kxd7 1/2-1/2 {agreed} code >  =SOMA Algorithm= Based on the program's name with its swap-off feature, SOMA has become an acronym for //**S**wapping **O**ff **M**aterial **A**nalyzer//, as a statical analysis of all possible capture-move sequences. Some early chess programs had no quiescence search but performed a SOMA like exchange evaluation, for instance Schach, Coko, Schach MV 5,6, early Sargon and Rebel versions, and notably programs by Richard Lang and Jeff Rollason. Dan and Kathe Spracklen credit Donald Michie and his 1974 book //On Machine Intelligence// as a reference:

In the domain of Computer Shogi, Jeff Rollason proposed an algorithm called SUPER-SOMA, an enhanced SOMA algorithm with Shogi-specific features.

=See also=
 * Acronym
 * Ed's Lookup from Attack and Defend Maps
 * Machiavelli
 * MVV-LVA
 * SEE - The Swap Algorithm
 * Static Exchange Evaluation
 * Swap-off by Helmut Richter
 * Turochamp

=Publications=
 * John Maynard Smith, Donald Michie (**1961**). //Machines that play games//. [|New Scientist], 12, 367-9. [|google books]
 * Donald Michie (**1966**). //Game Playing and Game Learning Automata.// Advances in Programming and Non-Numerical Computation, [|Leslie Fox] (ed.), pp. 183-200. Oxford, Pergamon. Includes Appendix: //Rules of SOMAC// by John Maynard Smith
 * Donald Michie (**1974**). //On Machine Intelligence//. Edinburgh: University Press, ISBN 10: 085224262X, ISBN 13: 9780852242629, [|abebooks.com], [|alibris.com], [|biblio.com]
 * Dan Spracklen, Kathe Spracklen (**1978**). //[|An Exchange Evaluator for Computer Chess]//. BYTE, Vol. 3, No. 11
 * Jeff Rollason (**2000**). //[|SUPER-SOMA - Solving Tactical Exchanges in Shogi without Tree Searching]//. CG 2000, [|Word preprint]
 * Hiroyuki Iida, Makoto Sakuta, Jeff Rollason (**2002**). //Computer Shogi//. Artificial Intelligence, Vol. 134, [|Elsevier], [|CiteSeerX]
 * Jeff Rollason (**2006**). //[|Looking for Alternatives to Quiescence Search]//. AI Factory, Autumn 2006

=Forum Posts= > [|Re: Computer Chess: swap down evaluators vs capture search] by Deniz Yuret, rgc, October 26, 1994
 * [|Computer Chess: swap down evaluators vs capture search] by Jon Dart, rgc, October 24, 1994 » Quiescence Search
 * [|Re: Movei added to Crafty vs Rybka comaprison data] by Edsel Apostol, CCC, June 06, 2007
 * [|SOMA] by Gerd Isenberg, CCC, July 04, 2009

=External Links= > media type="custom" key="24676356"
 * [|Soma (disambiguation) from Wikipedia]
 * [|Soma from Wikipedia]
 * [|Perikaryon from Wikipedia]
 * [|Soma cube from Wikipedia]
 * [|The Smashing Pumpkins] - [|Soma], [|Terminal 5], October 18, 2011, [|YouTube] Video

=References= =What links here?= include page="SOMA" component="backlinks" limit="40"
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