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Subject: Re: Stalemating swindle

Author: Richard Pijl

Date: 07:44:12 11/27/02

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On November 27, 2002 at 08:16:04, Alastair Scott wrote:

>[D] 7R/8/8/8/4k1p1/4p3/1r4rP/4R2K w - -
>
>In this position (White against Ruffian 1.0.1 on a PIIIM/1.2GHz, 256MB RAM, 19MB
>hash) I had been angling for stalemate tricks for some time and finally saw my
>chance:
>
>60. Rh3 gxh3
>61. Rxe3+
>
>It took a _long_ time (over 40 seconds) for Ruffian to realise that this
>position was drawn (evaluation dropping from ~-6.5 to 0.00). How long does it
>take other programs?

I had special detection code for rambling rooks in the Baron, but removed that
in 0.99.3 as it fired wrongly in certain cases. This means that Baron 0.99.4
beta 1 doesn't find the draw.

Baron 0.36 (containing the rambling rook detection code) has no problem
detecting the draw, it spots it immediately, showing Kxe3 as the PV. When backup
up to the diagram position it doesn't show the draw anymore. The reason is that
Baron considers 60..gxh3 a mistake, enabling the draw. Instead, Baron 0.36 will
play 60..Rge2!

I have been thinking a lot about a better way to detect perpetual check's but
haven't implemented anything yet.

Richard.



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