// Get the material key of Position out of the given endgame key code
// like "KBPKN". The trick here is to first forge an ad-hoc FEN string
- // and then let a Position object do the work for us. Note that the
- // FEN string could correspond to an illegal position.
+ // and then let a Position object do the work for us.
Key key(const string& code, Color c) {
assert(code.length() > 0 && code.length() < 8);
std::transform(sides[c].begin(), sides[c].end(), sides[c].begin(), tolower);
- string fen = sides[0] + char('0' + int(8 - code.length()))
- + sides[1] + "/8/8/8/8/8/8/8 w - - 0 10";
+ string fen = sides[0] + char(8 - sides[0].length() + '0') + "/8/8/8/8/8/8/"
+ + sides[1] + char(8 - sides[1].length() + '0') + " w - - 0 10";
return Position(fen, false, NULL).material_key();
}
add<KRKN>("KRKN");
add<KQKP>("KQKP");
add<KQKR>("KQKR");
- add<KBBKN>("KBBKN");
add<KNPK>("KNPK");
add<KNPKB>("KNPKB");
}
-/// KBB vs KN. This is almost always a win. We try to push the enemy king to a corner
-/// and away from his knight. For a reference of this difficult endgame see:
-/// en.wikipedia.org/wiki/Chess_endgame#Effect_of_tablebases_on_endgame_theory
-
-template<>
-Value Endgame<KBBKN>::operator()(const Position& pos) const {
-
- assert(verify_material(pos, strongSide, 2 * BishopValueMg, 0));
- assert(verify_material(pos, weakSide, KnightValueMg, 0));
-
- Square winnerKSq = pos.king_square(strongSide);
- Square loserKSq = pos.king_square(weakSide);
- Square knightSq = pos.list<KNIGHT>(weakSide)[0];
-
- Value result = VALUE_KNOWN_WIN
- + PushToCorners[loserKSq]
- + PushClose[square_distance(winnerKSq, loserKSq)]
- + PushAway[square_distance(loserKSq, knightSq)];
-
- return strongSide == pos.side_to_move() ? result : -result;
-}
-
-
/// Some cases of trivial draws
template<> Value Endgame<KNNK>::operator()(const Position&) const { return VALUE_DRAW; }
-template<> Value Endgame<KmmKm>::operator()(const Position&) const { return VALUE_DRAW; }
/// KB and one or more pawns vs K. It checks for draws with rook pawns and