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Update 5 search params for pruning at shallow depth
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Found by spsa tuning at 45+0.45 with:

```
int fpcEvalOffset = 188;
int fpcLmrDepthMult = 206;
int histDepthMult = -3232;
int histDenom = 5793;
int fpEvalOffset = 115;
int negSeeDepthMultSq = -27;
TUNE(SetRange(0, 394), fpcEvalOffset);
TUNE(SetRange(0, 412), fpcLmrDepthMult);
TUNE(SetRange(-6464, -1616), histDepthMult);
TUNE(SetRange(2896, 11586), histDenom);
TUNE(SetRange(0, 230), fpEvalOffset);
TUNE(SetRange(-54, 0), negSeeDepthMultSq);
```

Passed STC:
https://tests.stockfishchess.org/tests/view/6535551de746e058e6c0165d
LLR: 2.98 (-2.94,2.94) <0.00,2.00>
Total: 109056 W: 28025 L: 27599 D: 53432
Ptnml(0-2): 357, 12669, 28038, 13119, 345

Passed LTC:
https://tests.stockfishchess.org/tests/view/65364c6ff127f3553505175d
LLR: 2.94 (-2.94,2.94) <0.50,2.50>
Total: 61290 W: 15316 L: 14941 D: 31033
Ptnml(0-2): 34, 6849, 16498, 7236, 28

closes official-stockfish#4847

bench 1167412
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linrock authored and vondele committed Oct 24, 2023
1 parent ec02714 commit 0024133
Showing 1 changed file with 4 additions and 4 deletions.
8 changes: 4 additions & 4 deletions src/search.cpp
Original file line number Diff line number Diff line change
Expand Up @@ -974,7 +974,7 @@ Value search(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth, boo
{
Piece capturedPiece = pos.piece_on(to_sq(move));
int futilityEval =
ss->staticEval + 188 + 206 * lmrDepth + PieceValue[capturedPiece]
ss->staticEval + 239 + 291 * lmrDepth + PieceValue[capturedPiece]
+ captureHistory[movedPiece][to_sq(move)][type_of(capturedPiece)] / 7;
if (futilityEval < alpha)
continue;
Expand All @@ -991,16 +991,16 @@ Value search(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth, boo
+ (*contHist[3])[movedPiece][to_sq(move)];

// Continuation history based pruning (~2 Elo)
if (lmrDepth < 6 && history < -3232 * depth)
if (lmrDepth < 6 && history < -3498 * depth)
continue;

history += 2 * thisThread->mainHistory[us][from_to(move)];

lmrDepth += history / 5793;
lmrDepth += history / 7815;
lmrDepth = std::max(lmrDepth, -2);

// Futility pruning: parent node (~13 Elo)
if (!ss->inCheck && lmrDepth < 13 && ss->staticEval + 115 + 122 * lmrDepth <= alpha)
if (!ss->inCheck && lmrDepth < 13 && ss->staticEval + 80 + 122 * lmrDepth <= alpha)
continue;

lmrDepth = std::max(lmrDepth, 0);
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