const int NoPawnsSF[4] = { 6, 12, 32 };
// Polynomial material balance parameters
- const Value RedundantQueen = Value(320);
- const Value RedundantRook = Value(554);
+ const Value RedundantMajor = Value(160);
// pair pawn knight bishop rook queen
- const int LinearCoefficients[6] = { 1617, -162, -1172, -190, 105, 26 };
+ const int LinearCoefficients[6] = { 1852, -162, -1122, -183, 302, 1 };
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
+ { 58, 29, 83, 148, -163, 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
+ { 106, 101, 3, 151, 171, 0 } // Queen
};
// Endgame evaluation and scaling functions accessed direcly and not through
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];
+ // Penalty for major piece redundancy
+ if (pieceCount[Us][ROOK] + pieceCount[Us][QUEEN] > 1)
+ value -= RedundantMajor;
// 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)
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];
if (e->key == key)
return e;
- memset(e, 0, sizeof(Entry));
+ std::memset(e, 0, sizeof(Entry));
e->key = key;
e->factor[WHITE] = e->factor[BLACK] = (uint8_t)SCALE_FACTOR_NORMAL;
e->gamePhase = game_phase(pos);
}
}
- // No pawns makes it difficult to win, even with a material advantage
+ // No pawns makes it difficult to win, even with a material advantage. This
+ // catches some trivial draws like KK, KBK and KNK
if (!pos.count<PAWN>(WHITE) && npm_w - npm_b <= BishopValueMg)
{
e->factor[WHITE] = (uint8_t)
int minorPieceCount = pos.count<KNIGHT>(WHITE) + pos.count<BISHOP>(WHITE)
+ pos.count<KNIGHT>(BLACK) + pos.count<BISHOP>(BLACK);
- e->spaceWeight = minorPieceCount * minorPieceCount;
+ e->spaceWeight = make_score(minorPieceCount * minorPieceCount, 0);
}
// Evaluate the material imbalance. We use PIECE_TYPE_NONE as a place holder