Author: Ricardo Gibert
Date: 22:07:47 02/06/04
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On February 06, 2004 at 23:39:40, Uri Blass wrote: >On February 06, 2004 at 22:46:15, Ricardo Gibert wrote: > >>On February 06, 2004 at 13:48:48, Jaime Benito de Valle Ruiz wrote: >> >>>This endgame study can be game following the sequence >>> >>>1.Bd1 g1Q 2.Bxa4 Qc1 3.Bxd7 h5 4.Be8 h4 5.Ba4 Line >>> >>>[d] 8/3p4/p6p/k2N3B/p7/K6p/PP4pP/8 w - - 0 1 >>> >>>Many engines (Fritz 8, Hiarcs 8, Ruffian 1.01) cannot win this endgame, probably >>>due to the well known null-move problem for extreme and rare positions such as >>>this. >> >>These programs have an obvious bug in their implementation of null move. They >>should not be using stalemate as a fail high for a null move. Stalemate is tempo >>dependent thing and null move mucks up the tempi. You can think of stalemate as >>an obvious sort of zugzwang. Note, that it doesn't matter which side gets >>stalemated after a null move. The stalemate should be treated as a fail low for >>the null moving side regardless. > >I see no stalemate. 1.Bd1 g1Q 2.Bxa4 Qc1 3.Bxd7 h5 4.Be8 h4 5.Ba4 black_null_move 6. Bd7 Qxb2+ 7.Kxb2 stalemate. > >black has a queen after Ba4(see the corrected second diagram) and the queen has >to move but every place that the queen go is bad. > >Uri
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