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Remove log depth reduction terms. #6257

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Remove log depth reduction terms. #6257

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16 changes: 8 additions & 8 deletions src/search.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1177,27 +1177,27 @@ Value Search::Worker::search(

// These reduction adjustments have no proven non-linear scaling

r += 700 - 6 * msb(depth); // Base reduction offset to compensate for other tweaks
r -= moveCount * (64 - 2 * msb(depth));
r += 671; // Base reduction offset to compensate for other tweaks
r -= moveCount * 66;
r -= std::abs(correctionValue) / 30450;

// Increase reduction for cut nodes
if (cutNode)
r += 3092 + 2 * msb(depth) + (980 + 15 * msb(depth)) * !ttData.move;
r += 3094 + 1056 * !ttData.move;

// Increase reduction if ttMove is a capture
if (ttCapture)
r += 1467 - 40 * msb(depth);
r += 1415;

// Increase reduction if next ply has a lot of fail high
if ((ss + 1)->cutoffCnt > 2)
r += 1041 + 34 * msb(depth) + allNode * (752 + 226 * msb(depth));
r += 1051 + allNode * 814;

r += (ss + 1)->quietMoveStreak * 50;

// For first picked move (ttMove) reduce reduction
if (move == ttData.move)
r -= 2096 + 27 * msb(depth);
r -= 2018;

if (capture)
ss->statScore = 803 * int(PieceValue[pos.captured_piece()]) / 128
Expand All @@ -1208,7 +1208,7 @@ Value Search::Worker::search(
+ (*contHist[1])[movedPiece][move.to_sq()];

// Decrease/increase reduction for moves with a good/bad history
r -= ss->statScore * (734 - 12 * msb(depth)) / 8192;
r -= ss->statScore * 794 / 8192;

// Step 17. Late moves reduction / extension (LMR)
if (depth >= 2 && moveCount > 1)
Expand Down Expand Up @@ -1250,7 +1250,7 @@ Value Search::Worker::search(
{
// Increase reduction if ttMove is not present
if (!ttData.move)
r += 1178 + 35 * msb(depth);
r += 1118;

if (depth < 5)
r += 1080;
Expand Down