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Endgame malus for having a king in a pawnless flank

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Original idea by "ElbertoOne", while "FauziAkram" suggested to put a
small midgame penalty too.

STC:
LLR: 2.95 (-2.94,2.94) [0.00,5.00]
Total: 71808 W: 13038 L: 12610 D: 46160

LTC:
LLR: 2.95 (-2.94,2.94) [0.00,5.00]
Total: 150874 W: 19828 L: 19221 D: 111825

Bench: 6077005
This commit is contained in:
Stéphane Nicolet 2016-10-24 22:09:09 +02:00 • committed by Marco Costalba
parent e77f38c431
commit 818b4a126d
1 changed files with 7 additions and 1 deletions
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8
src/evaluate.cpp
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@ -198,6 +198,7 @@ namespace {
const Score Hanging = S(48, 27);
const Score ThreatByPawnPush = S(38, 22);
const Score Unstoppable = S( 0, 20);
const Score PawnlessFlank = S(20, 80);
// Penalty for a bishop on a1/h1 (a8/h8 for black) which is trapped by
// a friendly pawn on b2/g2 (b7/g7 for black). This can obviously only
@ -482,7 +483,8 @@ namespace {
}
// King tropism: firstly, find squares that opponent attacks in our king flank
b = ei.attackedBy[Them][ALL_PIECES] & KingFlank[Us][file_of(ksq)];
File kf = file_of(ksq);
b = ei.attackedBy[Them][ALL_PIECES] & KingFlank[Us][kf];
assert(((Us == WHITE ? b << 4 : b >> 4) & b) == 0);
assert(popcount(Us == WHITE ? b << 4 : b >> 4) == popcount(b));
@ -494,6 +496,10 @@ namespace {
score -= CloseEnemies * popcount(b);
// Penalty when our king is on a pawnless flank
if (!(pos.pieces(PAWN) & (KingFlank[WHITE][kf] | KingFlank[BLACK][kf])))
score -= PawnlessFlank;
if (DoTrace)
Trace::add(KING, Us, score);