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Subject: Re: Another anti null-mover engine position (and endgame study)

Author: Ricardo Gibert

Date: 19:46:15 02/06/04

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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.

>
>They just don't find 5. Ba4
>
>Try your engine after 4...,h4
>
>[d]8/3p4/p6p/k2N3B/p7/K6p/PP4pP/8 w - - 0 1
>
>All the above mentioned engines play 5.Bd7 and get a draw instead of winning.
>
>Regards,
>
>  Jaime

• Re: Another anti null-mover engine position (and endgame study) Tim Foden 00:04:51 02/07/04
  • Re: Another anti null-mover engine position (and endgame study) Uri Blass 12:31:55 02/07/04
• Re: Another anti null-mover engine position (and endgame study) Uri Blass 20:39:40 02/06/04
  • Re: Another anti null-mover engine position (and endgame study) Ricardo Gibert 22:07:47 02/06/04
    • Re: Another anti null-mover engine position (and endgame study) Ricardo Gibert 22:21:08 02/06/04

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