In this position
[d] 3k4/4r3/2R4P/4K1P1/8/3bB3/8/8 w - - 9 62
Weini playing white, without endgame table, at short TC, choose to defend with rook e6, black of course choose to exchange rooks after that.
There is a simple heuristic in Weini that says "you'd better exchange pieces if you have more pawn" ; and this is the case here ! But it failed badly ! as the resulting position is a draw.
Should I remove this heuristic or add something to detect this kind of "likely draw" position ?
Are they some engines, not using endgame table, that still have some draw detection code (that include positions with still some pieces on the board) I can have a look at ? Or should I go directly to syzygy implementation ?
without endgame table
Moderators: hgm, Rebel, chrisw
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Re: without endgame table
Ok Vajolet endgame.cpp is a good answer ...
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Re: without endgame table
and eval_draw.cpp in Rodent_III has some nice code.
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Re: without endgame table
and of course endgame.cpp in stockfish ... ok I have some code to read ...
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Re: without endgame table
The heuristic is in general good. When you have KRRPPKRR it would certainly be good strategy to simplify to KRPPKR. But in addition you should have code to recognize drawish end-games. Unlike Bishops is a special case of those, and the score of such end-games with an imbalance of 2 or fewer Pawns should be discounted by a factor ~2. So effectively the trade reduces the advantage from 2 Pawns to 1 Pawn, because in KBPPKB with unlike B it only counts half. This should be enough to outweigh the bonus for simplification.
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Re: without endgame table
I will try this tomorrow, thanks a lot.