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Simplify away conthist 3 from statscore

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Following previous elo gainer that gained by making conthist 3 less important in pruning this patch simplifies away this history from calculation of statscore.

Passed STC:
https://tests.stockfishchess.org/tests/view/6637aa7e9819650825aa93e0
LLR: 3.00 (-2.94,2.94) <-1.75,0.25>
Total: 35392 W: 9352 L: 9120 D: 16920
Ptnml(0-2): 141, 4145, 8888, 4385, 137

Passed LTC:
https://tests.stockfishchess.org/tests/view/66383cd8493aaaf4b7ea90c5
LLR: 2.94 (-2.94,2.94) <-1.75,0.25>
Total: 33948 W: 8714 L: 8503 D: 16731
Ptnml(0-2): 39, 3701, 9270, 3938, 26

closes https://github.com/official-stockfish/Stockfish/pull/5220

Bench: 2508571
This commit is contained in:
Michael Chaly 2024-05-06 20:18:12 +03:00 • committed by Joost VandeVondele
parent 9d6dab06a8
commit 3b4ddf4ae6
1 changed files with 7 additions and 5 deletions
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12
src/search.cpp
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@ -1149,8 +1149,7 @@ moves_loop: // When in check, search starts here
ss->statScore = 2 * thisThread->mainHistory[us][move.from_to()]
+ (*contHist[0])[movedPiece][move.to_sq()]
+ (*contHist[1])[movedPiece][move.to_sq()]
+ (*contHist[3])[movedPiece][move.to_sq()] - 5078;
+ (*contHist[1])[movedPiece][move.to_sq()] - 5078;
// Decrease/increase reduction for moves with a good/bad history (~8 Elo)
r -= ss->statScore / (17662 - std::min(depth, 16) * 105);
@ -1569,9 +1568,12 @@ Value Search::Worker::qsearch(Position& pos, Stack* ss, Value alpha, Value beta,
break;
// Continuation history based pruning (~3 Elo)
if (!capture && (*contHist[0])[pos.moved_piece(move)][move.to_sq()]
+ (*contHist[1])[pos.moved_piece(move)][move.to_sq()]
+ thisThread->pawnHistory[pawn_structure_index(pos)][pos.moved_piece(move)][move.to_sq()] <= 4000)
if (!capture
&& (*contHist[0])[pos.moved_piece(move)][move.to_sq()]
+ (*contHist[1])[pos.moved_piece(move)][move.to_sq()]
+ thisThread->pawnHistory[pawn_structure_index(pos)][pos.moved_piece(move)]
[move.to_sq()]
<= 4000)
continue;
// Do not search moves with bad enough SEE values (~5 Elo)