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53ab32e)
Retire KmmKm evaluation function. Instead give a very drawish
scale factor when the material advantage is small and not much
material remains.
Retire NoPawnsSF array. Pawnless endgames without a bishop will
now be scored higher. Pawnless endgames with a bishop pair will
be scored lower. The effect of this is hopefully small.
Consistent results both at short TC (fixed games):
ELO: -0.00 +-2.1 (95%) LOS: 50.0%
Total: 40000 W: 7405 L: 7405 D: 25190
And long TC (fixed games):
ELO: 0.77 +-1.9 (95%) LOS: 78.7%
Total: 39690 W: 6179 L: 6091 D: 27420
bench:
7213723
/// Some cases of trivial draws
template<> Value Endgame<KNNK>::operator()(const Position&) const { return VALUE_DRAW; }
/// 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
/// KB and one or more pawns vs K. It checks for draws with rook pawns and
KRKN, // KR vs KN
KQKP, // KQ vs KP
KQKR, // KQ vs KR
KRKN, // KR vs KN
KQKP, // KQ vs KP
KQKR, // KQ vs KR
- KmmKm, // K and two minors vs K and one or two minors
const Value MidgameLimit = Value(15581);
const Value EndgameLimit = Value(3998);
const Value MidgameLimit = Value(15581);
const Value EndgameLimit = Value(3998);
- // Scale factors used when one side has no more pawns
- const int NoPawnsSF[4] = { 6, 12, 32 };
-
// Polynomial material balance parameters
// pair pawn knight bishop rook queen
// Polynomial material balance parameters
// pair pawn knight bishop rook queen
// 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 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) };
Endgame<KBPsK> ScaleKBPsK[] = { Endgame<KBPsK>(WHITE), Endgame<KBPsK>(BLACK) };
Endgame<KXK> EvaluateKXK[] = { Endgame<KXK>(WHITE), Endgame<KXK>(BLACK) };
Endgame<KBPsK> ScaleKBPsK[] = { Endgame<KBPsK>(WHITE), Endgame<KBPsK>(BLACK) };
- if (!pos.pieces(PAWN) && !pos.pieces(ROOK) && !pos.pieces(QUEEN))
- {
- // Minor piece endgame with at least one minor piece per side and
- // no pawns. Note that the case KmmK is already handled by KXK.
- assert((pos.pieces(WHITE, KNIGHT) | pos.pieces(WHITE, BISHOP)));
- assert((pos.pieces(BLACK, KNIGHT) | pos.pieces(BLACK, BISHOP)));
-
- if ( pos.count<BISHOP>(WHITE) + pos.count<KNIGHT>(WHITE) <= 2
- && pos.count<BISHOP>(BLACK) + pos.count<KNIGHT>(BLACK) <= 2)
- {
- e->evaluationFunction = &EvaluateKmmKm[pos.side_to_move()];
- return e;
- }
- }
-
// OK, we didn't find any special evaluation function for the current
// material configuration. Is there a suitable scaling function?
//
// OK, we didn't find any special evaluation function for the current
// material configuration. Is there a suitable scaling function?
//
}
// No pawns makes it difficult to win, even with a material advantage. This
}
// No pawns makes it difficult to win, even with a material advantage. This
- // catches some trivial draws like KK, KBK and KNK
+ // catches some trivial draws like KK, KBK and KNK and gives a very drawish
+ // scale factor for cases such as KRKBP and KmmKm (except for KBBKN).
if (!pos.count<PAWN>(WHITE) && npm_w - npm_b <= BishopValueMg)
{
if (!pos.count<PAWN>(WHITE) && npm_w - npm_b <= BishopValueMg)
{
- e->factor[WHITE] = (uint8_t)
- (npm_w == npm_b || npm_w < RookValueMg ? 0 : NoPawnsSF[std::min(pos.count<BISHOP>(WHITE), 2)]);
+ e->factor[WHITE] = npm_w < RookValueMg ? 0 : npm_b <= BishopValueMg ? 4 : 12;
}
if (!pos.count<PAWN>(BLACK) && npm_b - npm_w <= BishopValueMg)
{
}
if (!pos.count<PAWN>(BLACK) && npm_b - npm_w <= BishopValueMg)
{
- e->factor[BLACK] = (uint8_t)
- (npm_w == npm_b || npm_b < RookValueMg ? 0 : NoPawnsSF[std::min(pos.count<BISHOP>(BLACK), 2)]);
+ e->factor[BLACK] = npm_b < RookValueMg ? 0 : npm_w <= BishopValueMg ? 4 : 12;
}
if (pos.count<PAWN>(WHITE) == 1 && npm_w - npm_b <= BishopValueMg)
}
if (pos.count<PAWN>(WHITE) == 1 && npm_w - npm_b <= BishopValueMg)