HCha/Stockfish
1
0
Fork 0
mirror of https://github.com/HChaZZY/Stockfish.git synced 2025-12-22 01:56:58 +08:00
Code Issues Packages Projects Releases Wiki Activity

Tweak kingAttackersCount and KingAttackWeights

Browse Source 
Use the whole kingRing for pawn attackers instead of only the squares directly
around the king. This tends to give quite a lot more kingAttackersCount, so to
compensate and to avoid raising the  king danger too fast we lower the values
in the KingAttackWeights array a little bit.

STC:
LLR: 2.95 (-2.94,2.94) [0.00,4.00]
Total: 51892 W: 10723 L: 10369 D: 30800
http://tests.stockfishchess.org/tests/view/5af6d4dd0ebc5968e652428e

LTC:
LLR: 2.96 (-2.94,2.94) [0.00,4.00]
Total: 24536 W: 3737 L: 3515 D: 17284
http://tests.stockfishchess.org/tests/view/5af709890ebc5968e65242ac

Credits to user @xoroshiro for the idea of using the kingRing for pawn attackers.

How to continue? It seems that the KingAttackWeights[] array stores values
which are quite Elo-sensitive, yet they have not been tuned with SPSA recently.
There might be easy Elo points to get there.

Closes https://github.com/official-stockfish/Stockfish/pull/1597

Bench: 5282815
This commit is contained in:
Stéphane Nicolet
2018-05-13 07:20:39 +02:00
parent c163c2fcb0
commit bf01bd0755
2 changed files with 3 additions and 2 deletions
Download Patch File Download Diff File Expand all files Collapse all files

1
AUTHORS
View File

@@ -118,3 +118,4 @@ Tom Vijlbrief (tomtor)
Torsten Franz (torfranz) Torsten Franz (torfranz)
Uri Blass (uriblass) Uri Blass (uriblass)
Vince Negri Vince Negri
xoroshiro

4
src/evaluate.cpp
View File

@@ -89,7 +89,7 @@ namespace {
constexpr Value SpaceThreshold = Value(12222); constexpr Value SpaceThreshold = Value(12222);
// KingAttackWeights[PieceType] contains king attack weights by piece type // KingAttackWeights[PieceType] contains king attack weights by piece type
constexpr int KingAttackWeights[PIECE_TYPE_NB] = { 0, 0, 78, 56, 45, 11 }; constexpr int KingAttackWeights[PIECE_TYPE_NB] = { 0, 0, 77, 55, 44, 10 };
// Penalties for enemy's safe checks // Penalties for enemy's safe checks
constexpr int QueenSafeCheck = 780; constexpr int QueenSafeCheck = 780;
@@ -281,7 +281,7 @@ namespace {
else if (file_of(pos.square<KING>(Us)) == FILE_A) else if (file_of(pos.square<KING>(Us)) == FILE_A)
kingRing[Us] |= shift<EAST>(kingRing[Us]); kingRing[Us] |= shift<EAST>(kingRing[Us]);
kingAttackersCount[Them] = popcount(attackedBy[Us][KING] & pe->pawn_attacks(Them)); kingAttackersCount[Them] = popcount(kingRing[Us] & pe->pawn_attacks(Them));
kingAttacksCount[Them] = kingAttackersWeight[Them] = 0; kingAttacksCount[Them] = kingAttackersWeight[Them] = 0;
} }
else else