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Fix an assert in KBK endgame 

The endgame king + minor vs king is erroneusly
detected as king + minor vs king + minor

Here the fix is to detect king + minor earlier,
in particular to add these trivial cases to
endgame evaluation functions.

Spotted by Reuven Peleg

bench: 4727133
sf_4_base
Marco Costalba 2013-07-27 08:22:12 +02:00
parent 7487eb0dca
commit 6373e88b5b
2 changed files with 13 additions and 11 deletions
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19
src/endgame.cpp
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@ -89,7 +89,10 @@ namespace {
Endgames::Endgames() {
add<KK>("KK");
add<KPK>("KPK");
add<KBK>("KBK");
add<KNK>("KNK");
add<KNNK>("KNNK");
add<KBNK>("KBNK");
add<KRKP>("KRKP");
@ -410,17 +413,13 @@ Value Endgame<KBBKN>::operator()(const Position& pos) const {
}
/// K and two minors vs K and one or two minors or K and two knights against
/// king alone are always draw.
template<>
Value Endgame<KmmKm>::operator()(const Position&) const {
return VALUE_DRAW;
}
/// Some cases of trivial draws
template<> Value Endgame<KK>::operator()(const Position&) const { return VALUE_DRAW; }
template<> Value Endgame<KBK>::operator()(const Position&) const { return VALUE_DRAW; }
template<> Value Endgame<KNK>::operator()(const Position&) const { return VALUE_DRAW; }
template<> Value Endgame<KNNK>::operator()(const Position&) const { return VALUE_DRAW; }
template<> Value Endgame<KmmKm>::operator()(const Position&) const { return VALUE_DRAW; }
template<>
Value Endgame<KNNK>::operator()(const Position&) const {
return VALUE_DRAW;
}
/// K, bishop and one or more pawns vs K. It checks for draws with rook pawns and
/// a bishop of the wrong color. If such a draw is detected, SCALE_FACTOR_DRAW

5
src/endgame.h
View File

@ -33,6 +33,10 @@ enum EndgameType {
// Evaluation functions
KK, // K vs K
KBK, // KB vs K
KNK, // KN vs K
KNNK, // KNN vs K
KXK, // Generic "mate lone king" eval
KBNK, // KBN vs K
KPK, // KP vs K
@ -42,7 +46,6 @@ enum EndgameType {
KQKP, // KQ vs KP
KQKR, // KQ vs KR
KBBKN, // KBB vs KN
KNNK, // KNN vs K
KmmKm, // K and two minors vs K and one or two minors