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Improve handling of queen imbalance

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We double the bonus for potential threats by minors and rooks against
our queen, in case of "queen vs pieces imbalance". Hopefully this will
improve a little bit the evaluation for this well-known Stockfish weakness.

passed STC:
LLR: 2.93 (-2.94,2.94) {-0.50,1.50}
Total: 72976 W: 14003 L: 13710 D: 45263
Ptnml(0-2): 1218, 8370, 17094, 8513, 1293
https://tests.stockfishchess.org/tests/view/5efa50eb020eec13834a977d

passed LTC:
LLR: 2.93 (-2.94,2.94) {0.25,1.75}
Total: 22232 W: 2779 L: 2560 D: 16893
Ptnml(0-2): 129, 1885, 6896, 2050, 156
https://tests.stockfishchess.org/tests/view/5f1fdd2dc09435d870cb9f13

closes https://github.com/official-stockfish/Stockfish/pull/2864

Bench: 4367349
This commit is contained in:
Stéphane Nicolet
2020-07-28 10:08:09 +02:00
parent 62d3106caa
commit 33f3cfae00
1 changed files with 7 additions and 3 deletions
Download Patch File Download Diff File Expand all files Collapse all files

10
src/evaluate.cpp
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@@ -579,17 +579,21 @@ namespace {
// Bonus for threats on the next moves against enemy queen // Bonus for threats on the next moves against enemy queen
if (pos.count<QUEEN>(Them) == 1) if (pos.count<QUEEN>(Them) == 1)
{ {
bool queenImbalance = pos.count<QUEEN>() == 1;
Square s = pos.square<QUEEN>(Them); Square s = pos.square<QUEEN>(Them);
safe = mobilityArea[Us] & ~stronglyProtected; safe = mobilityArea[Us]
& ~pos.pieces(Us, PAWN)
& ~stronglyProtected;
b = attackedBy[Us][KNIGHT] & attacks_bb<KNIGHT>(s); b = attackedBy[Us][KNIGHT] & attacks_bb<KNIGHT>(s);
score += KnightOnQueen * popcount(b & safe); score += KnightOnQueen * popcount(b & safe) * (1 + queenImbalance);
b = (attackedBy[Us][BISHOP] & attacks_bb<BISHOP>(s, pos.pieces())) b = (attackedBy[Us][BISHOP] & attacks_bb<BISHOP>(s, pos.pieces()))
| (attackedBy[Us][ROOK ] & attacks_bb<ROOK >(s, pos.pieces())); | (attackedBy[Us][ROOK ] & attacks_bb<ROOK >(s, pos.pieces()));
score += SliderOnQueen * popcount(b & safe & attackedBy2[Us]); score += SliderOnQueen * popcount(b & safe & attackedBy2[Us]) * (1 + queenImbalance);
} }
if (T) if (T)