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Make pruning at ttpv nodes more aggressive

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Continuation of work done by @FauziAkram and @Viren6 They had a series
of patches that decrease pruning for ttPv nodes - and it passed as a
gainer at lower time controls while revert passed as a gainer at higher
time controls.
So it's a logical continuation of this work that increases pruning for
ttPv nodes in hopes of scaling to longer TCs.

Fixed games STC:
https://tests.stockfishchess.org/tests/view/679ee3910774dfd78deb0efd
Elo: -4.98 ± 2.1 (95%) LOS: 0.0%
Total: 28584 W: 7229 L: 7639 D: 13716
Ptnml(0-2): 143, 3579, 7219, 3247, 104
nElo: -9.54 ± 4.0 (95%) PairsRatio: 0.90

Passed VVLTC with STC bounds:
https://tests.stockfishchess.org/tests/view/679d21f70774dfd78deaf553
LLR: 2.94 (-2.94,2.94) <0.00,2.00>
Total: 323282 W: 83729 L: 83105 D: 156448
Ptnml(0-2): 37, 29842, 101269, 30446, 47

Passed VVLTC with LTC bounds:
https://tests.stockfishchess.org/tests/view/679e7a970774dfd78deb0cd3
LLR: 2.95 (-2.94,2.94) <0.50,2.50>
Total: 113712 W: 29485 L: 29051 D: 55176
Ptnml(0-2): 13, 10376, 35640, 10818, 9

closes https://github.com/official-stockfish/Stockfish/pull/5844

Bench: 2964045
This commit is contained in:
Michael Chaly
2025-02-02 06:06:13 +03:00
committed by Disservin
parent 344e89275a
commit dabffbceff
1 changed files with 7 additions and 1 deletions
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src/search.cpp
+7 -1
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@@ -999,6 +999,12 @@ moves_loop: // When in check, search starts here
Depth r = reduction(improving, depth, moveCount, delta); Depth r = reduction(improving, depth, moveCount, delta);
// Increase reduction for ttPv nodes (*Scaler)
// Smaller or even negative value is better for short time controls
// Bigger value is better for long time controls
if (ss->ttPv)
r += 1024;
// Step 14. Pruning at shallow depth. // Step 14. Pruning at shallow depth.
// Depth conditions are important for mate finding. // Depth conditions are important for mate finding.
if (!rootNode && pos.non_pawn_material(us) && !is_loss(bestValue)) if (!rootNode && pos.non_pawn_material(us) && !is_loss(bestValue))
@@ -1156,7 +1162,7 @@ moves_loop: // When in check, search starts here
// Decrease reduction for PvNodes (*Scaler) // Decrease reduction for PvNodes (*Scaler)
if (ss->ttPv) if (ss->ttPv)
r -= 1037 + (ttData.value > alpha) * 965 + (ttData.depth >= depth) * 960; r -= 2061 + (ttData.value > alpha) * 965 + (ttData.depth >= depth) * 960;
if (PvNode) if (PvNode)
r -= 1018; r -= 1018;