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| Subject: Latest abrok Development Version November 24th (SF The gift that keeps on giving ) Sun Nov 24, 2019 2:03 pm | |
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Windows x64 for Haswell CPUs Windows x64 for modern computers Windows x64 Windows 32 Linux x64 for Haswell CPUs Linux x64 for modern computers Linux x64 | Author: 31m059 Date: Sun Nov 24 00:34:43 2019 +0100 Timestamp: 1574552083 King danger: retire attacked-by-bishop defense In a recent commit, "Introduce king flank defenders," a term was introduced by Michael Chaly (@Vizvezdenec) to reduce king danger based on king defenders, i.e., friendly attacks on our King Flank and Camp. This is a powerful idea and broadly applicable to all of our pieces. An earlier, but narrower, version of a similar idea was already coded into king danger, with a term reducing king danger simply if we had a bishop and king attacking the same square -- there is also a similar term for knights, but roughly three times larger. I had attempted to tweak this term's coefficient fairly recently, in a series of tests in early September which increased this coefficient. All failed STC with significantly negative scores. Now that the king flank defenders term has been introduced, it appears that the bishop-defense term can be simplified away without compensation or significant Elo loss. Where do we go from here? This PR is a natural follow-up to "Introduce king flank defenders," which proposed simplification with existing and overlapping terms, such as this one. That PR also mentioned that the coefficient it introduced appeared arbitrary, so perhaps this PR can facilitate a tweak to increase king flank defenders' coefficient. Additionally, this pull request is extremely similar to https://github.com/official-stockfish/Stockfish/pull/1821, which was (coincidentally) merged a year ago, to the day (November 23, 2018). That patch also simplified away a linear king danger tropism term, which was soon after replaced with a quadratic term by @Vizvezdenec (which would not have passed without the simplification). @Vizvezdenec, again by coincidence, has recently been trying to implement a quadratic term, this time for defenders rather than attackers. This history of this evaluation code suggests that this simplification might be enough to help a patch for quadratic king-flank defenders pass. Bench: 4959670 STC: LLR: 2.94 (-2.94,2.94) [-3.00,1.00] Total: 22209 W: 4920 L: 4800 D: 12489 Elo +1.88 https://tests.stockfishchess.org/tests/view/5dd444d914339111b9b6bed7 LTC: LLR: 2.95 (-2.94,2.94) [-3.00,1.00] Total: 152107 W: 24658 L: 24743 D: 102706 Elo -0.19 https://tests.stockfishchess.org/tests/view/5dd4be31f531e81cf278ea9d Interesting discussion on Github about this pull request: https://github.com/official-stockfish/Stockfish/pull/2424 --- This pull request was opened less than one week before the holiday of Thanksgiving here in the United States. In keeping with the holiday tradition of expressing gratitude, I would like to thank our generous CPU donors, talented forum contributors, innovative developers, speedy fishtest approvers, and especially our hardworking server maintainers (@ppigazzini and @tomtor). Thank you all for a year of great Stockfish progress! | Windows x64 for Haswell CPUs Windows x64 for modern computers Windows x64 Windows 32 Linux x64 for Haswell CPUs Linux x64 for modern computers Linux x64 | Author: SFisGOD Date: Sun Nov 24 00:23:06 2019 +0100 Timestamp: 1574551386 Simplify endgame factor for opposite colored bishops Stockfish is continually improving. Patches that gain elo in the past may no longer be needed as stockfish improved elsewhere. This patch removes passed pawns count dependence in opposite colored bishops scale factor. We used the mean of passed count pawns (~1.4) to compensate, and changed the base value from 16 to 22. Passed STC: LLR: 2.95 (-2.94,2.94) [-3.00,1.00] Total: 57879 W: 12657 L: 12607 D: 32615 Elo +0.30 http://tests.stockfishchess.org/tests/view/5dd1644f42928ff08153dc1e Passed LTC: LLR: 2.95 (-2.94,2.94) [-3.00,1.00] Total: 121648 W: 19622 L: 19659 D: 82367 Elo -0.11 http://tests.stockfishchess.org/tests/view/5dd24572ccb823d41d4b47bb Closes https://github.com/official-stockfish/Stockfish/pull/2419 Bench: 5067864 |
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