Author: Robert Hyatt
Date: 08:26:27 06/09/01
Go up one level in this thread
On June 09, 2001 at 05:09:57, Ferdinand S. Mosca wrote: >On June 08, 2001 at 11:16:42, Robert Hyatt wrote: > >>On June 08, 2001 at 01:53:58, Ferdinand S. Mosca wrote: >> >>> >>>Hello Bob, >>> >>>I have been examining games on my tournament among winboard engines >>>and found this position which Crafty should have not played. >>> >>>Comet B.33 - Crafty 18.9 >>>[D]8/8/1n6/2b2B2/5B1k/3p4/5P2/5K2 b - - 0 62 >>>Here Crafty played 62...Bxf2?? with an evaluation of 0.0 >>>on P3 668mhz. >>> >>>My Nalimov EGTB which is from Hiarcs 7.32 CD >>>does not include KBBKN, which I think not even related >>>here because it is clear that the two bishops >>>will win against a knight. >> >>Sorry, but 2B's don't always win against a knight. If you take the >>position after Bxf2 Kxf2, and remove the final pawn, this is a dead >>drawn tablebase ending. The KBBKN tablebase will show this pretty >>easily. > >Hi Bob, > >Normally 2B's will often win against a knight and 2B's normally will not win >against 1B. BTW according to Jeremiah, from other post, Bxf2 is mate in 44 >moves. > >I guess the current version of Crafty running without complete 5-man EGTB is >weak at minor piece ending. Not enough, when both sides have rooks and Crafty is >slightly inferior, it will exhange rooks and goes for an inferior minor piece >ending which it thought a complete drawish. Interesting to look at the databases >now. Testing with position set up is also very nice. > I did some random probes. In reasonable positions, KBB vs KN is not won very often. And overall, K**K* where * is any minor piece is almost always drawn when yuou consider all the possible pieces that * could be. Crafty uses this basic piece of "knowledge" to go for what should be the easy "draw" here (it enters a K** vs K*P ending which is drawn by its simple rule. I might fix this one day, but 99.999% of the time it is correct. IE I have seen many positions where it was KRNP vs KRBP where the opponent's pawn was way advanced. It will take the pawn in an instant, leaving it in a totally drawn KRN vs KRP (it has the R and P). >Maybe it's time to increase the disk space too!! > >Regards, >Dinan > >> >> >> >>> >>>I disabled the EGTB and still Crafty likes to play >>>Bxf2. I have tried the Chessbase Crafty 18.08 with the same result. >>> >>>Maybe someone will verify this on their unit. >>> >>> >>>Regards, >>>Dinan
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