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Do more negative extensions

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This patch does negatively extend transposition table move if singular search failed and tt value is not bigger than alpha.
Logic is close to what we had before recent simplification of negative extensions but uses or condition instead of and condition.

Passed STC:
https://tests.stockfishchess.org/tests/view/6404c8102644b62c33934607
LLR: 2.94 (-2.94,2.94) <0.00,2.00>
Total: 119040 W: 31841 L: 31416 D: 55783
Ptnml(0-2): 356, 13070, 32292, 13397, 405

Passed LTC:
https://tests.stockfishchess.org/tests/view/6405abda2644b62c33937119
LLR: 2.94 (-2.94,2.94) <0.50,2.50>
Total: 47216 W: 12816 L: 12496 D: 21904
Ptnml(0-2): 12, 4500, 14286, 4776, 34

closes https://github.com/official-stockfish/Stockfish/pull/4430

bench 4747020
This commit is contained in:
Michael Chaly 2023-03-07 01:54:20 +03:00 • committed by Joost VandeVondele
parent 6ce225bb4c
commit 39da50ed23
1 changed files with 4 additions and 0 deletions
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4
src/search.cpp
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@ -1109,6 +1109,10 @@ moves_loop: // When in check, search starts here
// If the eval of ttMove is less than value, we reduce it (negative extension)
else if (ttValue <= value)
extension = -1;
// If the eval of ttMove is less than alpha, we reduce it (negative extension)
else if (ttValue <= alpha)
extension = -1;
}
// Check extensions (~1 Elo)