Author: Uri Blass
Date: 14:07:10 12/08/00
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On December 08, 2000 at 16:52:46, Robert Hyatt wrote: >On December 08, 2000 at 15:25:06, Torstein Hall wrote: > >>On December 08, 2000 at 14:47:37, Dann Corbit wrote: >> >>>[D]2r3k1/5p2/1p2pp1p/pPq5/Pn6/1B6/1P2QPPP/3R2K1 w - - 0 25 >>> >>>It seems some programs get the right answer immediately (e.g. Phalanx) and >>>others simply never find it. >>> >>>My question is, "Why?" >>> >>>I tried programs that don't do NULL move, and that did not seem to help. So >>>what is preventing programs from finding the right choice? >> >>...and Bxe6 is the right move I guess!? >> >>Found by Gambit Tiger in a split second >> >>Torstein > > >You can find this one of two ways. You give up a piece for potentially three >pawns + no king safety for black. If this were all there is, it would be a >mistake as white is a piece down. But there is more. Going deep enough, black >has to give the piece back, and white simply ends up winning a pawn, period. > >It is not hard to make any program like this. Crafty hates the idea of giving >a piece for three pawns because 90% of the time that loses. I agree that a piece is better than 3 pawns in most of the cases but I think that it is an exagaration to say that in 90% of the cases the knight is winning. There are many cases when knight for 3 pawns is a draw. It has to see the >"meat" before it will "bite". Which takes 14 plies and 3-4 minutes on my xeon. >If a program has big scores for king safety, it will probably bite on this >instantly. If not, it will have search deep enough to see that black has to >sac the knight to avoid getting mated, leaving white a pawn up in what might >still be a drawn ending (both sides have pawns, plus rook and queen each. The main question is if white can win after Bxe6 fxe6 Qxe6+ Kh8 White can take 4 pawns for the piece but I do not see a forced win for white and I suspect that it is a draw. Black does not have to sac the knight in this line but only to sac a pawn. Uri
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