From: Joona Kiiski Date: Mon, 6 Sep 2010 07:53:10 +0000 (+0300) Subject: Retire pawn storm evaluation X-Git-Url: https://git.sesse.net/?p=stockfish;a=commitdiff_plain;h=fa2478a81f42648aa3382d60280e01adb0c4536f Retire pawn storm evaluation More then 100 lines of almost useless evaluations. Prefer code semplification to a very small and dubious advantage. After 7457 games on russian cluster: Mod - Orig: 1285 - 1334 - 4838 ELO -2 (+- 3.2) Signed-off-by: Marco Costalba --- diff --git a/src/evaluate.cpp b/src/evaluate.cpp index 664f3e85..72dc73a1 100644 --- a/src/evaluate.cpp +++ b/src/evaluate.cpp @@ -336,26 +336,11 @@ Value do_evaluate(const Position& pos, Value margins[]) { Phase phase = mi->game_phase(); - // Middle-game specific evaluation terms - if (phase > PHASE_ENDGAME) + // Evaluate space for both sides, only in middle-game. + if (phase > PHASE_ENDGAME && mi->space_weight() > 0) { - // Evaluate pawn storms in positions with opposite castling - if ( square_file(pos.king_square(WHITE)) >= FILE_E - && square_file(pos.king_square(BLACK)) <= FILE_D) - - bonus += make_score(ei.pi->queenside_storm_value(WHITE) - ei.pi->kingside_storm_value(BLACK), 0); - - else if ( square_file(pos.king_square(WHITE)) <= FILE_D - && square_file(pos.king_square(BLACK)) >= FILE_E) - - bonus += make_score(ei.pi->kingside_storm_value(WHITE) - ei.pi->queenside_storm_value(BLACK), 0); - - // Evaluate space for both sides - if (mi->space_weight() > 0) - { - int s = evaluate_space(pos, ei) - evaluate_space(pos, ei); - bonus += apply_weight(make_score(s * mi->space_weight(), 0), Weights[Space]); - } + int s = evaluate_space(pos, ei) - evaluate_space(pos, ei); + bonus += apply_weight(make_score(s * mi->space_weight(), 0), Weights[Space]); } // If we don't already have an unusual scale factor, check for opposite diff --git a/src/pawns.cpp b/src/pawns.cpp index c314c4ae..37a54dd9 100644 --- a/src/pawns.cpp +++ b/src/pawns.cpp @@ -70,36 +70,6 @@ namespace { S(34,68), S(83,166), S(0, 0), S( 0, 0) }; - // Pawn storm tables for positions with opposite castling - const int QStormTable[64] = { - 0, 0, 0, 0, 0, 0, 0, 0, - -22,-22,-22,-14,-6, 0, 0, 0, - -6,-10,-10,-10,-6, 0, 0, 0, - 4, 12, 16, 12, 4, 0, 0, 0, - 16, 23, 23, 16, 0, 0, 0, 0, - 23, 31, 31, 23, 0, 0, 0, 0, - 23, 31, 31, 23, 0, 0, 0, 0, - 0, 0, 0, 0, 0, 0, 0, 0 - }; - - const int KStormTable[64] = { - 0, 0, 0, 0, 0, 0, 0, 0, - 0, 0, 0,-10,-19,-28,-33,-33, - 0, 0, 0,-10,-15,-19,-24,-24, - 0, 0, 0, 0, 1, 1, 1, 1, - 0, 0, 0, 0, 1, 10, 19, 19, - 0, 0, 0, 0, 1, 19, 31, 27, - 0, 0, 0, 0, 0, 22, 31, 22, - 0, 0, 0, 0, 0, 0, 0, 0 - }; - - // Pawn storm open file bonuses by file - const int16_t QStormOpenFileBonus[8] = { 31, 31, 18, 0, 0, 0, 0, 0 }; - const int16_t KStormOpenFileBonus[8] = { 0, 0, 0, 0, 0, 26, 42, 26 }; - - // Pawn storm lever bonuses by file - const int StormLeverBonus[8] = { -8, -8, -13, 0, 0, -13, -8, -8 }; - #undef S } @@ -175,35 +145,22 @@ Score PawnInfoTable::evaluate_pawns(const Position& pos, Bitboard ourPawns, Square s; File f; Rank r; - int bonus; bool passed, isolated, doubled, opposed, chain, backward, candidate; Score value = SCORE_ZERO; const Square* ptr = pos.piece_list_begin(Us, PAWN); - // Initialize pawn storm scores by giving bonuses for open files + // Initialize halfOpenFiles[] for (f = FILE_A; f <= FILE_H; f++) if (!(ourPawns & file_bb(f))) - { - pi->ksStormValue[Us] += KStormOpenFileBonus[f]; - pi->qsStormValue[Us] += QStormOpenFileBonus[f]; pi->halfOpenFiles[Us] |= (1 << f); - } // Loop through all pawns of the current color and score each pawn while ((s = *ptr++) != SQ_NONE) { - f = square_file(s); - r = square_rank(s); - assert(pos.piece_on(s) == piece_of_color_and_type(Us, PAWN)); - // Calculate kingside and queenside pawn storm scores for both colors to be - // used when evaluating middle game positions with opposite side castling. - bonus = (f >= FILE_F ? evaluate_pawn_storm(s, r, f, theirPawns) : 0); - pi->ksStormValue[Us] += KStormTable[relative_square(Us, s)] + bonus; - - bonus = (f <= FILE_C ? evaluate_pawn_storm(s, r, f, theirPawns) : 0); - pi->qsStormValue[Us] += QStormTable[relative_square(Us, s)] + bonus; + f = square_file(s); + r = square_rank(s); // Our rank plus previous one. Used for chain detection. b = rank_bb(r) | rank_bb(Us == WHITE ? r - Rank(1) : r + Rank(1)); @@ -288,35 +245,3 @@ Score PawnInfoTable::evaluate_pawns(const Position& pos, Bitboard ourPawns, return value; } - -/// PawnInfoTable::evaluate_pawn_storm() evaluates each pawn which seems -/// to have good chances of creating an open file by exchanging itself -/// against an enemy pawn on an adjacent file. - -template -int PawnInfoTable::evaluate_pawn_storm(Square s, Rank r, File f, Bitboard theirPawns) const { - - const Bitboard StormFilesBB = (Side == KingSide ? FileFBB | FileGBB | FileHBB - : FileABB | FileBBB | FileCBB); - const int K = (Side == KingSide ? 2 : 4); - const File RookFile = (Side == KingSide ? FILE_H : FILE_A); - - Bitboard b = attack_span_mask(Us, s) & theirPawns & StormFilesBB; - int bonus = 0; - - while (b) - { - // Give a bonus according to the distance of the nearest enemy pawn - Square s2 = pop_1st_bit(&b); - Rank r2 = square_rank(s2); - int v = StormLeverBonus[f] - K * rank_distance(r, r2); - - // If enemy pawn has no pawn beside itself is particularly vulnerable. - // Big bonus, especially against a weakness on the rook file - if (!(theirPawns & neighboring_files_bb(s2) & rank_bb(s2))) - v *= (square_file(s2) == RookFile ? 4 : 2); - - bonus += v; - } - return bonus; -} diff --git a/src/pawns.h b/src/pawns.h index 76a98566..0e7ca61d 100644 --- a/src/pawns.h +++ b/src/pawns.h @@ -47,8 +47,6 @@ class PawnInfo { public: Score pawns_value() const; - Value kingside_storm_value(Color c) const; - Value queenside_storm_value(Color c) const; Bitboard pawn_attacks(Color c) const; Bitboard passed_pawns(Color c) const; int file_is_half_open(Color c, File f) const; @@ -67,8 +65,6 @@ private: Bitboard pawnAttacks[2]; Square kingSquares[2]; Score value; - int ksStormValue[2]; - int qsStormValue[2]; int halfOpenFiles[2]; Score kingShelters[2]; }; @@ -92,9 +88,6 @@ private: template Score evaluate_pawns(const Position& pos, Bitboard ourPawns, Bitboard theirPawns, PawnInfo* pi) const; - template - int evaluate_pawn_storm(Square s, Rank r, File f, Bitboard theirPawns) const; - PawnInfo* entries; }; @@ -118,14 +111,6 @@ inline Bitboard PawnInfo::pawn_attacks(Color c) const { return pawnAttacks[c]; } -inline Value PawnInfo::kingside_storm_value(Color c) const { - return Value(ksStormValue[c]); -} - -inline Value PawnInfo::queenside_storm_value(Color c) const { - return Value(qsStormValue[c]); -} - inline Bitboard PawnInfo::passed_pawns(Color c) const { return passedPawns[c]; }