Author: James T. Walker
Date: 08:56:42 04/11/01
Go up one level in this thread
On April 11, 2001 at 11:27:09, Robert Hyatt wrote: >On April 11, 2001 at 03:01:27, Ernst Walet wrote: > >>On April 10, 2001 at 23:23:21, Derek wrote: >> >>>This position is a study that I saw on the following website: >>>http://www.chesscafe.com/endgame/endgame.htm >>> >>>White: Kc5,Nd5,Ng6,Bh7 >>>Black: Ka5,Ba2,a3 >>> >>>White to move >>> >>>Rebel-Tiger 14.0, using all 3,4, and 5-man tablebases >>> >>>After the moves: >>> >>>1.Nc3 Bb1 2.Nxb1 a2 3.Nd2 > >Bb1 is probably not the best move. It leads to an instant mate in 30 >according to crafty, while Be6 prolongs it. > >Nxb1 a2 Nd2 leaves things at a mate in 29 for white. > >a1=B changes it to a mate in 12. > >There is a bug somewhere. I would suspect that the program is recognizing that >KBNN vs KB is somehow a draw, when it is not. It ends up as a KBN vs K ending >or a KBNN vs K ending, either of which is easily won. > > >>> >>>Tiger analyzes 3...a1=Q as lost for Black, but shows 3...a1=B as a draw for >>>Black. This is clearly incorrect, as after 4 Nb3+ Ka4 5 Nxa1, it's evaluation >>>changes to show that Black is mated in 10 moves. Is this a serious evaluation >>>error in the program? >> >> >>What happens if you disable the tablebases? >> >>Ernst. > > >That would be a good test... There appears to be a serious problem here with Tiger. With tablebases off and after 2...a2 Tiger plays Nd2 expecting a1=N which I guess is OK. But if I play a1=B Tiger instantly plays Nc4+ with score of 0.00. Tiger expects to see Ka4 Nb6 Ka3 Nc4 Ka4 to repeat and draw. ?? With tablebases on, after 2....a2 Tiger plays Nd2 expecting Ka6. If I play a1=B again Tiger again plays Nc4+?? scored 0.00. Definitely a bug somewhere.
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