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Double weight of pawn history for quiet move ordering.

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I measured on my 1000 position bench the average additional added pawn history per depth.
This shows on average negative value with even smaller values with increaing depth.

A linear regression against depth get following formula:

-1960 - 130 * depth

For compensation add this to the used sort limit to maintain roughly the same proportion of sorted quiet moves.

Remarks:
1. using no compensation failed here https://tests.stockfishchess.org/tests/view/6547664f136acbc5735265f0
2. using only the compensation failed at LTC:
   passed STC: https://tests.stockfishchess.org/tests/view/65477457136acbc5735266f8
   failed LTC: https://tests.stockfishchess.org/tests/view/65487fc8136acbc573527d1c

STC:
LLR: 2.94 (-2.94,2.94) <0.00,2.00>
Total: 98528 W: 25109 L: 24699 D: 48720
Ptnml(0-2): 334, 11586, 25009, 12006, 329
https://tests.stockfishchess.org/tests/view/65475873136acbc5735264f7

LTC:
LLR: 2.95 (-2.94,2.94) <0.50,2.50>
Total: 69726 W: 17467 L: 17073 D: 35186
Ptnml(0-2): 39, 7814, 18769, 8196, 45
https://tests.stockfishchess.org/tests/view/6547e759136acbc573527071

closes https://github.com/official-stockfish/Stockfish/pull/4866

Bench: 1379422
This commit is contained in:
Stefan Geschwentner 2023-11-06 16:12:30 +01:00 • committed by Joost VandeVondele
parent d0e87104aa
commit 80b0e37543
1 changed files with 2 additions and 2 deletions
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4
src/movepick.cpp
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@ -181,12 +181,12 @@ void MovePicker::score() {
// histories
m.value = 2 * (*mainHistory)[pos.side_to_move()][from_to(m)];
m.value += 2 * (*pawnHistory)[pawn_structure(pos)][pc][to];
m.value += 2 * (*continuationHistory[0])[pc][to];
m.value += (*continuationHistory[1])[pc][to];
m.value += (*continuationHistory[2])[pc][to] / 4;
m.value += (*continuationHistory[3])[pc][to];
m.value += (*continuationHistory[5])[pc][to];
m.value += (*pawnHistory)[pawn_structure(pos)][pc][to];
// bonus for checks
m.value += bool(pos.check_squares(pt) & to) * 16384;
@ -302,7 +302,7 @@ top:
endMoves = generate<QUIETS>(pos, cur);
score<QUIETS>();
partial_insertion_sort(cur, endMoves, -3000 * depth);
partial_insertion_sort(cur, endMoves, -1960 - 3130 * depth);
}
++stage;