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Change definition of "weak" in threats calculation

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By defining "strongly protected" as "protected by a pawn, or protected
by two pieces and not attacked by two enemy pieces".

Passed STC:
LLR: 2.97 (-2.94,2.94) [0.00,5.00]
Total: 17050 W: 3128 L: 2931 D: 10991

Passed LTC:
LLR: 2.96 (-2.94,2.94) [0.00,5.00]
Total: 120995 W: 15852 L: 15343 D: 89800

Bench : 6269229

Closes #1016
This commit is contained in:
snicolet 2017-02-25 17:43:54 -08:00 • committed by Joona Kiiski
parent f1e3dfea74
commit 8f7e032b8c
1 changed files with 15 additions and 10 deletions
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21
src/evaluate.cpp
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@ -525,7 +525,7 @@ namespace {
const Bitboard TRank2BB = (Us == WHITE ? Rank2BB : Rank7BB);
const Bitboard TRank7BB = (Us == WHITE ? Rank7BB : Rank2BB);
Bitboard b, weak, defended, safeThreats;
Bitboard b, weak, defended, stronglyProtected, safeThreats;
Score score = SCORE_ZERO;
// Non-pawn enemies attacked by a pawn
@ -545,12 +545,18 @@ namespace {
score += ThreatBySafePawn[type_of(pos.piece_on(pop_lsb(&safeThreats)))];
}
// Non-pawn enemies defended by a pawn
defended = (pos.pieces(Them) ^ pos.pieces(Them, PAWN)) & ei.attackedBy[Them][PAWN];
// Squares strongly protected by the opponent, either because they attack the
// square with a pawn, or because they attack the square twice and we don't.
stronglyProtected = ei.attackedBy[Them][PAWN]
| (ei.attackedBy2[Them] & ~ei.attackedBy2[Us]);
// Enemies not defended by a pawn and under our attack
// Non-pawn enemies, strongly protected
defended = (pos.pieces(Them) ^ pos.pieces(Them, PAWN))
& stronglyProtected;
// Enemies not strongly protected and under our attack
weak = pos.pieces(Them)
& ~ei.attackedBy[Them][PAWN]
& ~stronglyProtected
& ei.attackedBy[Us][ALL_PIECES];
// Add a bonus according to the kind of attacking pieces
@ -675,8 +681,8 @@ namespace {
mbonus += rr + r * 2, ebonus += rr + r * 2;
} // rr != 0
// Scale down bonus for candidate passers which need more than one pawn
// push to become passed.
// Scale down bonus for candidate passers which need more than one
// pawn push to become passed.
if (!pos.pawn_passed(Us, s + pawn_push(Us)))
mbonus /= 2, ebonus /= 2;
@ -686,7 +692,6 @@ namespace {
if (DoTrace)
Trace::add(PASSED, Us, score);
// Add the scores to the middlegame and endgame eval
return score;
}