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Double weight of pawn history for quiet move ordering.
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 official-stockfish#4866 Bench: 1379422
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