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NCM plays each Stockfish dev build 20,000 times against Stockfish 14. This yields an approximate Elo difference and establishes confidence in the strength of the dev builds.


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Commit ID 82d66f6b72c656a3efc4fd54b6eb489a8f74a945
Author 31m059
Date 2019-07-11 21:05:28 UTC
Exclude passed pawns from Attacked2Unsupported We recently added a bonus for double pawn attacks on unsupported enemy pawns, on June 27. However, it is possible that the unsupported pawn may become a passer by simply pushing forward out of the double attack. By rewarding double attacks, we may inadvertently reward the creation of enemy passers, by encouraging both of our would-be stoppers to attack the enemy pawn even if there is no opposing friendly pawn on the same file. Here, we revise this term to exclude passed pawns. In order to simplify the code with this change included, we non-functionally rewrite Attacked2Unsupported to be a penalty for enemy attacks on friendly pawns, rather than a bonus for our attacks on enemy pawns. This allows us to exclude passed pawns with a simple & ~e->passedPawns[Us], while passedPawns[Them] is not yet defined in this part of the code. This dramatically reduces the proportion of positions in which Attacked2Unsupported is applied, to about a third of the original. To compensate, maintaining the same average effect across our bench positions, we nearly triple Attacked2Unsupported from S(0, 20) to S(0, 56). Although this pawn formation is rare, it is worth more than half a pawn in the endgame! STC: (stopped automatically by fishtest after 250,000 games) LLR: -0.87 (-2.94,2.94) [0.50,4.50] Total: 250000 W: 56585 L: 55383 D: 138032 LTC: LLR: 2.96 (-2.94,2.94) [0.00,3.50] Total: 81038 W: 13965 L: 13558 D: 53515 Closes Bench: 3765158
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