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Assign extra bonus for previous move that caused a fail low more often

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This patch allows to assign extra bonus for previous move that caused a fail low not only for PvNodes and cutNodes but also fo some allNodes - namely if the best result we could've got from the search is still far below alpha.

passed STC
https://tests.stockfishchess.org/tests/view/61aa26a49e8855bba1a36d96
LLR: 2.94 (-2.94,2.94) <0.00,2.50>
Total: 73808 W: 19183 L: 18842 D: 35783
Ptnml(0-2): 251, 8257, 19564, 8564, 268

passed LTC
https://tests.stockfishchess.org/tests/view/61aa7dc29e8855bba1a3814f
LLR: 2.94 (-2.94,2.94) <0.50,3.00>
Total: 142416 W: 36717 L: 36192 D: 69507
Ptnml(0-2): 106, 14799, 40862, 15346, 95

closes https://github.com/official-stockfish/Stockfish/pull/3835

bench 4724181
This commit is contained in:
Michael Chaly
2021-12-06 03:52:44 +03:00
committed by Joost VandeVondele
parent 7d44b43b3c
commit a3d425cf55
1 changed files with 9 additions and 1 deletions
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10
src/search.cpp
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@@ -1380,7 +1380,15 @@ moves_loop: // When in check, search starts here
// Bonus for prior countermove that caused the fail low
else if ( (depth >= 3 || PvNode)
&& !priorCapture)
update_continuation_histories(ss-1, pos.piece_on(prevSq), prevSq, stat_bonus(depth) * (1 + (PvNode || cutNode)));
{
//Assign extra bonus if current node is PvNode or cutNode
//or fail low was really bad
bool extraBonus = PvNode
|| cutNode
|| bestValue < alpha - 94 * depth;
update_continuation_histories(ss-1, pos.piece_on(prevSq), prevSq, stat_bonus(depth) * (1 + extraBonus));
}
if (PvNode)
bestValue = std::min(bestValue, maxValue);