From: snicolet Date: Sun, 26 Feb 2017 01:43:54 +0000 (-0800) Subject: Change definition of "weak" in threats calculation X-Git-Url: https://git.sesse.net/?a=commitdiff_plain;h=8f7e032b8c8c2c19e37ece09eecb589fe2342daa;p=stockfish Change definition of "weak" in threats calculation 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 --- diff --git a/src/evaluate.cpp b/src/evaluate.cpp index 84c83269..9224ce2a 100644 --- a/src/evaluate.cpp +++ b/src/evaluate.cpp @@ -181,10 +181,10 @@ namespace { S(-20,-12), S( 1, -8), S( 2, 10), S( 9, 10) }; - // Protector[PieceType][distance] contains a protecting bonus for our king, + // Protector[PieceType][distance] contains a protecting bonus for our king, // indexed by piece type and distance between the piece and the king. const Score Protector[PIECE_TYPE_NB][8] = { - {}, {}, + {}, {}, { S(0, 0), S( 7, 9), S( 7, 1), S( 1, 5), S(-10,-4), S( -1,-4), S( -7,-3), S(-16,-10) }, // Knight { S(0, 0), S(11, 8), S(-7,-1), S(-1,-2), S( -1,-7), S(-11,-3), S( -9,-1), S(-16, -1) }, // Bishop { S(0, 0), S(10, 0), S(-2, 2), S(-5, 4), S( -6, 2), S(-14,-3), S( -2,-9), S(-12, -7) }, // Rook @@ -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]); + + // Non-pawn enemies, strongly protected + defended = (pos.pieces(Them) ^ pos.pieces(Them, PAWN)) + & stronglyProtected; - // Enemies not defended by a pawn and under our attack + // 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; }