X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fmaterial.cpp;h=b8152f7d2870db93ec92331025f9e247e48f332d;hp=0f1e19b9ee4a954f69bb84844e9227110f21709a;hb=8bfb53efe21c314695220a76ab5555492a3cf94a;hpb=27f2ce8f6e8462bd9be4b201dd95fc2df17aafe6 diff --git a/src/material.cpp b/src/material.cpp index 0f1e19b9..b8152f7d 100644 --- a/src/material.cpp +++ b/src/material.cpp @@ -1,7 +1,7 @@ /* Stockfish, a UCI chess playing engine derived from Glaurung 2.1 Copyright (C) 2004-2008 Tord Romstad (Glaurung author) - Copyright (C) 2008-2013 Marco Costalba, Joona Kiiski, Tord Romstad + Copyright (C) 2008-2014 Marco Costalba, Joona Kiiski, Tord Romstad Stockfish is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by @@ -31,40 +31,34 @@ namespace { const Value MidgameLimit = Value(15581); const Value EndgameLimit = Value(3998); - // Scale factors used when one side has no more pawns - const int NoPawnsSF[4] = { 6, 12, 32 }; - // Polynomial material balance parameters - const Value RedundantQueen = Value(320); - const Value RedundantRook = Value(554); // pair pawn knight bishop rook queen - const int LinearCoefficients[6] = { 1617, -162, -1172, -190, 105, 26 }; + const int LinearCoefficients[6] = { 1852, -162, -1122, -183, 249, -157 }; const int QuadraticCoefficientsSameColor[][PIECE_TYPE_NB] = { // pair pawn knight bishop rook queen - { 7 }, // Bishop pair + { 0 }, // Bishop pair { 39, 2 }, // Pawn { 35, 271, -4 }, // Knight - { 7, 105, 4, 7 }, // Bishop - { -27, -2, 46, 100, 56 }, // Rook - { 58, 29, 83, 148, -3, -25 } // Queen + { 0, 105, 4, 0 }, // Bishop + { -27, -2, 46, 100, -141 }, // Rook + {-161, 30, 126, 144, -127, 0 } // Queen }; const int QuadraticCoefficientsOppositeColor[][PIECE_TYPE_NB] = { // THEIR PIECES // pair pawn knight bishop rook queen - { 41 }, // Bishop pair - { 37, 41 }, // Pawn - { 10, 62, 41 }, // Knight OUR PIECES - { 57, 64, 39, 41 }, // Bishop - { 50, 40, 23, -22, 41 }, // Rook - { 106, 101, 3, 151, 171, 41 } // Queen + { 0 }, // Bishop pair + { 37, 0 }, // Pawn + { 10, 62, 0 }, // Knight OUR PIECES + { 57, 64, 39, 0 }, // Bishop + { 50, 40, 23, -22, 0 }, // Rook + { 103, 90, -40, 142, 268, 0 } // Queen }; - // Endgame evaluation and scaling functions accessed direcly and not through - // the function maps because correspond to more then one material hash key. - Endgame EvaluateKmmKm[] = { Endgame(WHITE), Endgame(BLACK) }; + // Endgame evaluation and scaling functions are accessed directly and not through + // the function maps because they correspond to more than one material hash key. Endgame EvaluateKXK[] = { Endgame(WHITE), Endgame(BLACK) }; Endgame ScaleKBPsK[] = { Endgame(WHITE), Endgame(BLACK) }; @@ -95,7 +89,7 @@ namespace { && pos.count(Them) >= 1; } - /// imbalance() calculates imbalance comparing piece count of each + /// imbalance() calculates the imbalance by comparing the piece count of each /// piece type for both colors. template @@ -106,14 +100,8 @@ namespace { int pt1, pt2, pc, v; int value = 0; - // Redundancy of major pieces, formula based on Kaufman's paper - // "The Evaluation of Material Imbalances in Chess" - if (pieceCount[Us][ROOK] > 0) - value -= RedundantRook * (pieceCount[Us][ROOK] - 1) - + RedundantQueen * pieceCount[Us][QUEEN]; - // Second-degree polynomial material imbalance by Tord Romstad - for (pt1 = NO_PIECE_TYPE; pt1 <= QUEEN; pt1++) + for (pt1 = NO_PIECE_TYPE; pt1 <= QUEEN; ++pt1) { pc = pieceCount[Us][pt1]; if (!pc) @@ -121,12 +109,13 @@ namespace { v = LinearCoefficients[pt1]; - for (pt2 = NO_PIECE_TYPE; pt2 <= pt1; pt2++) + for (pt2 = NO_PIECE_TYPE; pt2 <= pt1; ++pt2) v += QuadraticCoefficientsSameColor[pt1][pt2] * pieceCount[Us][pt2] + QuadraticCoefficientsOppositeColor[pt1][pt2] * pieceCount[Them][pt2]; value += pc * v; } + return value; } @@ -155,9 +144,9 @@ Entry* probe(const Position& pos, Table& entries, Endgames& endgames) { e->factor[WHITE] = e->factor[BLACK] = (uint8_t)SCALE_FACTOR_NORMAL; e->gamePhase = game_phase(pos); - // Let's look if we have a specialized evaluation function for this - // particular material configuration. First we look for a fixed - // configuration one, then a generic one if previous search failed. + // Let's look if we have a specialized evaluation function for this particular + // material configuration. Firstly we look for a fixed configuration one, then + // for a generic one if the previous search failed. if (endgames.probe(key, e->evaluationFunction)) return e; @@ -173,21 +162,6 @@ Entry* probe(const Position& pos, Table& entries, Endgames& endgames) { return e; } - if (!pos.pieces(PAWN) && !pos.pieces(ROOK) && !pos.pieces(QUEEN)) - { - // Minor piece endgame with at least one minor piece per side and - // no pawns. Note that the case KmmK is already handled by KXK. - assert((pos.pieces(WHITE, KNIGHT) | pos.pieces(WHITE, BISHOP))); - assert((pos.pieces(BLACK, KNIGHT) | pos.pieces(BLACK, BISHOP))); - - if ( pos.count(WHITE) + pos.count(WHITE) <= 2 - && pos.count(BLACK) + pos.count(BLACK) <= 2) - { - e->evaluationFunction = &EvaluateKmmKm[pos.side_to_move()]; - return e; - } - } - // OK, we didn't find any special evaluation function for the current // material configuration. Is there a suitable scaling function? // @@ -201,8 +175,8 @@ Entry* probe(const Position& pos, Table& entries, Endgames& endgames) { return e; } - // Generic scaling functions that refer to more then one material - // distribution. Should be probed after the specialized ones. + // Generic scaling functions that refer to more than one material + // distribution. They should be probed after the specialized ones. // Note that these ones don't return after setting the function. if (is_KBPsKs(pos)) e->scalingFunction[WHITE] = &ScaleKBPsK[WHITE]; @@ -219,7 +193,7 @@ Entry* probe(const Position& pos, Table& entries, Endgames& endgames) { Value npm_w = pos.non_pawn_material(WHITE); Value npm_b = pos.non_pawn_material(BLACK); - if (npm_w + npm_b == VALUE_ZERO) + if (npm_w + npm_b == VALUE_ZERO && pos.pieces(PAWN)) { if (!pos.count(BLACK)) { @@ -241,18 +215,19 @@ Entry* probe(const Position& pos, Table& entries, Endgames& endgames) { } // No pawns makes it difficult to win, even with a material advantage. This - // catches some trivial draws like KK, KBK and KNK + // catches some trivial draws like KK, KBK and KNK and gives a very drawish + // scale factor for cases such as KRKBP and KmmKm (except for KBBKN). if (!pos.count(WHITE) && npm_w - npm_b <= BishopValueMg) - { - e->factor[WHITE] = (uint8_t) - (npm_w == npm_b || npm_w < RookValueMg ? 0 : NoPawnsSF[std::min(pos.count(WHITE), 2)]); - } + e->factor[WHITE] = uint8_t(npm_w < RookValueMg ? SCALE_FACTOR_DRAW : npm_b <= BishopValueMg ? 4 : 12); if (!pos.count(BLACK) && npm_b - npm_w <= BishopValueMg) - { - e->factor[BLACK] = (uint8_t) - (npm_w == npm_b || npm_b < RookValueMg ? 0 : NoPawnsSF[std::min(pos.count(BLACK), 2)]); - } + e->factor[BLACK] = uint8_t(npm_b < RookValueMg ? SCALE_FACTOR_DRAW : npm_w <= BishopValueMg ? 4 : 12); + + if (pos.count(WHITE) == 1 && npm_w - npm_b <= BishopValueMg) + e->factor[WHITE] = (uint8_t) SCALE_FACTOR_ONEPAWN; + + if (pos.count(BLACK) == 1 && npm_b - npm_w <= BishopValueMg) + e->factor[BLACK] = (uint8_t) SCALE_FACTOR_ONEPAWN; // Compute the space weight if (npm_w + npm_b >= 2 * QueenValueMg + 4 * RookValueMg + 2 * KnightValueMg) @@ -264,7 +239,7 @@ Entry* probe(const Position& pos, Table& entries, Endgames& endgames) { } // Evaluate the material imbalance. We use PIECE_TYPE_NONE as a place holder - // for the bishop pair "extended piece", this allow us to be more flexible + // for the bishop pair "extended piece", which allows us to be more flexible // in defining bishop pair bonuses. const int pieceCount[COLOR_NB][PIECE_TYPE_NB] = { { pos.count(WHITE) > 1, pos.count(WHITE), pos.count(WHITE),