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Pawn Center Bind Bonus

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Bonus for two pawns controlling the same central square

STC:

LLR: 3.14 (-2.94,2.94) [-1.50,4.50]
Total: 15974 W: 3291 L: 3133 D: 9550

LTC:

LLR: 3.24 (-2.94,2.94) [0.00,6.00]
Total: 10449 W: 1837 L: 1674 D: 6938

Idea from Lyudmil Tsvetkov.

Bench: 7699138

Resolves #248
This commit is contained in:
Joona Kiiski 2015-02-08 19:20:39 +00:00 • committed by Joona Kiiski
parent 170bdf40cd
commit e118570038
1 changed files with 12 additions and 0 deletions
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12
src/pawns.cpp
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@ -61,6 +61,14 @@ namespace {
// Unsupported pawn penalty
const Score UnsupportedPawnPenalty = S(20, 10);
// Center bind bonus: Two pawns controlling the same central square
const Bitboard CenterBindMask[COLOR_NB] = {
(FileDBB | FileEBB) & (Rank5BB | Rank6BB | Rank7BB),
(FileDBB | FileEBB) & (Rank4BB | Rank3BB | Rank2BB)
};
const Score CenterBind = S(16, 0);
// Weakness of our pawn shelter in front of the king by [distance from edge][rank]
const Value ShelterWeakness[][RANK_NB] = {
{ V( 99), V(20), V(26), V(54), V(85), V( 92), V(108) },
@ -195,6 +203,10 @@ namespace {
b = e->semiopenFiles[Us] ^ 0xFF;
e->pawnSpan[Us] = b ? int(msb(b) - lsb(b)) : 0;
// Center binds: Two pawns controlling the same central square
b = shift_bb<Right>(ourPawns) & shift_bb<Left>(ourPawns) & CenterBindMask[Us];
score += popcount<Max15>(b) * CenterBind;
return score;
}