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Retire trapped bishop evaluation

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Another 100 lines of dubious and ad-hoc code.

After 7644 games on russian cluster:
Mod - Orig 1285 - 1249 - 5110  ELO +1 (+- 3.2)

Signed-off-by: Marco Costalba <mcostalba@gmail.com>
This commit is contained in:
Marco Costalba 2010-08-22 14:18:58 +01:00
parent e17fa64aec
commit 421867ea2d
1 changed files with 0 additions and 98 deletions
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98
src/evaluate.cpp
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@ -159,27 +159,6 @@ namespace {
// right to castle. // right to castle.
const Value TrappedRookPenalty = Value(180); const Value TrappedRookPenalty = Value(180);
// Penalty for a bishop on a7/h7 (a2/h2 for black) which is trapped by
// enemy pawns.
const Score TrappedBishopA7H7Penalty = make_score(300, 300);
// Bitboard masks for detecting trapped bishops on a7/h7 (a2/h2 for black)
const Bitboard MaskA7H7[2] = {
((1ULL << SQ_A7) | (1ULL << SQ_H7)),
((1ULL << SQ_A2) | (1ULL << SQ_H2))
};
// Penalty for a bishop on a1/h1 (a8/h8 for black) which is trapped by
// a friendly pawn on b2/g2 (b7/g7 for black). This can obviously only
// happen in Chess960 games.
const Score TrappedBishopA1H1Penalty = make_score(100, 100);
// Bitboard masks for detecting trapped bishops on a1/h1 (a8/h8 for black)
const Bitboard MaskA1H1[2] = {
((1ULL << SQ_A1) | (1ULL << SQ_H1)),
((1ULL << SQ_A8) | (1ULL << SQ_H8))
};
// The SpaceMask[color] contains the area of the board which is considered // The SpaceMask[color] contains the area of the board which is considered
// by the space evaluation. In the middle game, each side is given a bonus // by the space evaluation. In the middle game, each side is given a bonus
// based on how many squares inside this area are safe and available for // based on how many squares inside this area are safe and available for
@ -251,8 +230,6 @@ namespace {
template<Color Us> template<Color Us>
void evaluate_passed_pawns(const Position& pos, EvalInfo& ei); void evaluate_passed_pawns(const Position& pos, EvalInfo& ei);
void evaluate_trapped_bishop_a7h7(const Position& pos, Square s, Color us, EvalInfo& ei);
void evaluate_trapped_bishop_a1h1(const Position& pos, Square s, Color us, EvalInfo& ei);
inline Score apply_weight(Score v, Score weight); inline Score apply_weight(Score v, Score weight);
Value scale_by_game_phase(const Score& v, Phase ph, const ScaleFactor sf[]); Value scale_by_game_phase(const Score& v, Phase ph, const ScaleFactor sf[]);
Score weight_option(const std::string& mgOpt, const std::string& egOpt, Score internalWeight); Score weight_option(const std::string& mgOpt, const std::string& egOpt, Score internalWeight);
@ -559,17 +536,6 @@ namespace {
if ((Piece == BISHOP || Piece == KNIGHT) && pos.square_is_weak(s, Us)) if ((Piece == BISHOP || Piece == KNIGHT) && pos.square_is_weak(s, Us))
evaluate_outposts<Piece, Us>(pos, ei, s); evaluate_outposts<Piece, Us>(pos, ei, s);
// Special patterns: trapped bishops on a7/h7/a2/h2
// and trapped bishops on a1/h1/a8/h8 in Chess960.
if (Piece == BISHOP)
{
if (bit_is_set(MaskA7H7[Us], s))
evaluate_trapped_bishop_a7h7(pos, s, Us, ei);
if (Chess960 && bit_is_set(MaskA1H1[Us], s))
evaluate_trapped_bishop_a1h1(pos, s, Us, ei);
}
// Queen or rook on 7th rank // Queen or rook on 7th rank
if ( (Piece == ROOK || Piece == QUEEN) if ( (Piece == ROOK || Piece == QUEEN)
&& relative_rank(Us, s) == RANK_7 && relative_rank(Us, s) == RANK_7
@ -865,70 +831,6 @@ namespace {
} }
// evaluate_trapped_bishop_a7h7() determines whether a bishop on a7/h7
// (a2/h2 for black) is trapped by enemy pawns, and assigns a penalty
// if it is.
void evaluate_trapped_bishop_a7h7(const Position& pos, Square s, Color us, EvalInfo &ei) {
assert(square_is_ok(s));
assert(pos.piece_on(s) == piece_of_color_and_type(us, BISHOP));
Square b6 = relative_square(us, (square_file(s) == FILE_A) ? SQ_B6 : SQ_G6);
Square b8 = relative_square(us, (square_file(s) == FILE_A) ? SQ_B8 : SQ_G8);
if ( pos.piece_on(b6) == piece_of_color_and_type(opposite_color(us), PAWN)
&& pos.see(s, b6) < 0
&& pos.see(s, b8) < 0)
{
ei.value -= Sign[us] * TrappedBishopA7H7Penalty;
}
}
// evaluate_trapped_bishop_a1h1() determines whether a bishop on a1/h1
// (a8/h8 for black) is trapped by a friendly pawn on b2/g2 (b7/g7 for
// black), and assigns a penalty if it is. This pattern can obviously
// only occur in Chess960 games.
void evaluate_trapped_bishop_a1h1(const Position& pos, Square s, Color us, EvalInfo& ei) {
Piece pawn = piece_of_color_and_type(us, PAWN);
Square b2, b3, c3;
assert(Chess960);
assert(square_is_ok(s));
assert(pos.piece_on(s) == piece_of_color_and_type(us, BISHOP));
if (square_file(s) == FILE_A)
{
b2 = relative_square(us, SQ_B2);
b3 = relative_square(us, SQ_B3);
c3 = relative_square(us, SQ_C3);
}
else
{
b2 = relative_square(us, SQ_G2);
b3 = relative_square(us, SQ_G3);
c3 = relative_square(us, SQ_F3);
}
if (pos.piece_on(b2) == pawn)
{
Score penalty;
if (!pos.square_is_empty(b3))
penalty = 2 * TrappedBishopA1H1Penalty;
else if (pos.piece_on(c3) == pawn)
penalty = TrappedBishopA1H1Penalty;
else
penalty = TrappedBishopA1H1Penalty / 2;
ei.value -= Sign[us] * penalty;
}
}
// evaluate_space() computes the space evaluation for a given side. The // evaluate_space() computes the space evaluation for a given side. The
// space evaluation is a simple bonus based on the number of safe squares // space evaluation is a simple bonus based on the number of safe squares
// available for minor pieces on the central four files on ranks 2--4. Safe // available for minor pieces on the central four files on ranks 2--4. Safe