Win-Draw-Loss evaluation

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2023-03-19 13:00:06

Traditionally, computer chess engines evaluated position in terms of pawns. This is a convenient choice, as material is a foundation of position evaluation, which is true also among humans. Situations where the importance of positional aspect strongly outweights material are often thought as beautiful exceptions rather than the rule.

It is however not the most logical way to score a position. Using pawns sounds arbitrary, and it’s also not linear and the same step has different meanings: while going from 0 to 1 pawn advantage keeps the position quite holdable, going from 1 to 2 usually makes it mostly lost. Going from 10 to 11 makes no difference at all.

What other values can be used as an evaluation of the position? The natural choice appears to be using of probability of winning.

Probability of winning is the evaluation method that DeepMind chose for their AlphaGo and later AlphaZero engines. It’s also what LCZero used up to July 2019.

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