SEX+Algorithm


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 * [[image:420px-Sexual_cycle.svg.png width="360" link="https://commons.wikimedia.org/wiki/File:Sexual_cycle.svg"]] ||~  || The **SEX Algorithm** was a proposal by David Levy, David Broughton and Mark Taylor to apply Fractional extensions and reductions. It was introduced in 1989 in the ICGA Journal paper //The SEX Algorithm in Computer Chess// (**S**earch **EX**tension), applied in programs and dedicated computers developed by Intelligent Software in the 80s. Since "uninteresting moves" were decremented by up to 21 (forward moves) or 24 (backward moves), and the depth increment of the ID framework was 7 or 8, SEX implemented fractional reductions and even a kind of LMR in Cyrus 68K, considering early non-tactical moves from a evaluated sorted move list by a moderate SX decrement, and to determine the SXDEC values for its non-tactical siblings on the basis of their score differences. Forced tactical moves such as checks and captures were decremented by 3 to 7, and therefor extended by fractions of a ply, while late non-tactical moves were reduced by up to two and some fractional plies.

Beside static move properties and SEE, various other considerations were tried over the years from 1981 until 1988 to improve the algorithm and to distinguish between interesting and uninteresting moves, including game phase (eight phases 0..7), depth, Killer heuristic, Parity Pruning, two separate SEX-values for both sides, Mate threats and Mate at a Glance. || toc =Excerpts= from //The SEX Algorithm in Computer Chess// 1989 :
 * Life cycle of sexually reproducing organisms ||~  ||^   ||

The Foundation of the Search Algorithm
> math P(Mi) * P(Mij) * P(Mijk) math

> math log[P(Mi)] + log[P(Mij)] + log[P(Mijk)] math

The Measurement of "Interestingness"
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Refinements
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The Second Generation of the SEX Algorithm
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Chipography

 * Chess Champion Mark V -
 * Cyrus 68K -
 * Parker Chess -

=See also=
 * Fractional Extensions
 * Late Move Reductions

=Publications=

Algorithm

 * David Levy, David Broughton, Mark Taylor (**1989**). //The SEX Algorithm in Computer Chess//. ICCA Journal, Vol. 12, No. 1
 * Yoshimasa Tsuruoka, Daisaku Yokoyama, Takashi Chikayama (**2002**). //[|Game-Tree Search Algorithm based on Realization Probability]//. ICGA Journal, Vol. 25, No. 3
 * David Levy (**2002**). //[|SOME COMMENTS ON REALIZATION PROBABILITIES AND THE SEX ALGORITHM]//. ICGA Journal, Vol. 25, No. 3

Sex

 * David Levy (**2007**). //[|Love and Sex With Robots]: The Evolution of Human-Robot Relationships//. [|HarperCollins]

=External Links= > media type="youtube" key="AVZwejaNmbw"
 * [|Sex from Wikipedia]
 * [|Sexual reproduction from Wikipedia]
 * [|Evolution of sexual reproduction from Wikipedia]
 * [|Fertilisation from Wikipedia]
 * [|Meiosis from Wikipedia]
 * [|Ploidy from Wikipedia]
 * [|Sex (book) from Wikipedia]
 * [|Everything You Always Wanted to Know About Sex* (*But Were Afraid to Ask) - Wikipedia]
 * [|James Brown] - [|Sex Machine], 1971, [|Rai Storia], [|YouTube] Video

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