Asymmetric Evaluation

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Some programs score certain terms differently for the side they are playing and for the opponent. Most often the big terms, like king safety, passed pawn evaluation or mobility are scaled in some way. Whilst it might be argued that this idea runs counter the definition of chess as a zero-sum game, it also allows greater freedom in shaping the program's playing style. Richard Lang's programs were famous for their asymmetry in evaluation and forward pruning, which emphasis safety (rules like 'do not start a wild attack, but worry a lot if the opponent does so').

=See also=
 * Odd-Even Effect
 * Opponent Model Search
 * Parity Pruning
 * Tempo

=Publications=
 * Ingo Althöfer (1992). On Asymmetries in Chess Programs. ICCA Journal, Vol. 15, No. 1
 * Javier Ros Padilla (1994). Estimating Asymmetry and Selectivity in Chess Programs. ICCA Journal, Vol. 17, No. 1
 * David Carmel, Shaul Markovitch (1994). The M* Algorithm: Incorporating Opponent Models into Adversary Search. CIS Report #9402, pdf

=Forum Posts=

1997 ...

 * asymmetry by Andrew Tridgell, rgcc, August 12, 1997 » KnightCap, Parity Pruning
 * Re: Junior's long lines: more data about this... by Don Dailey, CCC, December 26, 1997
 * Genius' asymmetric-search by example: TRY yourself by Thorsten Czub, rgcc, December 30, 1997
 * Asymetric king safety by Tom King, rgcc, March 13, 1999

2000 ...

 * Parity of depth level and evaluation by Claude Le Page, CCC, June 13, 2005

2010 ...

 * evaluating color agnostic terms by Alvaro Cardoso, CCC, October 15, 2013
 * Different eval for white/black by Matthew Lai, CCC, January 05, 2015
 * Asymmetric evaluation function by Fabio Gobbato, CCC, July 24, 2015
 * Asymmetrical evaluation by Laurie Tunnicliffe, CCC, May 24, 2016 » Odd-Even Effect
 * Symmetrical evaluation and endgame by Hamfer, OpenChess Forum, June 02, 2016 » Tempo
 * Why Lc0 eval (in cp) is asymmetric against AB engines? by Kai Laskos, CCC, July 25, 2018 » Leela Chess Zero, Pawn Advantage, Win Percentage, and Elo

2020 ...

 * asymmetric evaluation and TT by Vivien Clauzon, CCC, June 02, 2020 » Transposition Table

=References= Up one Level