/*
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
const int NoPawnsSF[4] = { 6, 12, 32 };
// Polynomial material balance parameters
- const Value RedundantMajor = Value(160);
// pair pawn knight bishop rook queen
- const int LinearCoefficients[6] = { 1852, -162, -1122, -183, 302, 1 };
+ const int LinearCoefficients[6] = { 1852, -162, -1122, -183, 249, -52 };
const int QuadraticCoefficientsSameColor[][PIECE_TYPE_NB] = {
// pair pawn knight bishop rook queen
{ 106, 101, 3, 151, 171, 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 evaluation and scaling functions are accessed directly and not through
+ // the function maps because they correspond to more than one material hash key.
Endgame<KmmKm> EvaluateKmmKm[] = { Endgame<KmmKm>(WHITE), Endgame<KmmKm>(BLACK) };
Endgame<KXK> EvaluateKXK[] = { Endgame<KXK>(WHITE), Endgame<KXK>(BLACK) };
&& pos.count<PAWN>(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<Color Us>
int pt1, pt2, pc, v;
int value = 0;
- // 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)
{
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;
}
// Generic scaling functions that refer to more then one material
- // distribution. Should be probed after the specialized ones.
+ // distribution. They should be probed after the specialized ones.
// Note that these ones don't return after setting the function.
if (is_KBPsKs<WHITE>(pos))
e->scalingFunction[WHITE] = &ScaleKBPsK[WHITE];
(npm_w == npm_b || npm_b < RookValueMg ? 0 : NoPawnsSF[std::min(pos.count<BISHOP>(BLACK), 2)]);
}
+ if (pos.count<PAWN>(WHITE) == 1 && npm_w - npm_b <= BishopValueMg)
+ {
+ e->factor[WHITE] = (uint8_t) SCALE_FACTOR_ONEPAWN;
+ }
+
+ if (pos.count<PAWN>(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)
{
}
// 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<BISHOP>(WHITE) > 1, pos.count<PAWN>(WHITE), pos.count<KNIGHT>(WHITE),