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Subject: Re: Junior: really a 2554 program as SSDF list claims?

Author: John Stanback

Date: 13:40:59 02/17/99

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On February 16, 1999 at 21:17:30, Howard Exner wrote:

>On February 16, 1999 at 18:56:17, John Stanback wrote:
>
>>On February 15, 1999 at 20:48:35, Howard Exner wrote:
>>
>>>On February 15, 1999 at 03:22:50, Jouni Uski wrote:
>>>
>>>>In was quite surprised, that in two consecutine(!) tournament game between
>>>>Junior 5 and Crafty 16.3 Junior eats a7 pawn with bishop. So after b6 bishop is
>>>>lost. I have never seen Mchess or Rebel even considering that. Hmmm...
>>>
>>>7k/ppp1bpp1/7p/8/8/1P1PB2P/1P3PP1/5K2 w
>>>
>>>Is this the kind of example you were considering?
>>>Sometimes its ok to take the pawn as the bishop can escape
>>>but in the above example it would be a relatively easy task for
>>>a human to avoid the move Bxa7. How do programs handle this position?
>>
>>Zarkov has knowledge for this and does not take the pawn, but plays Ke2.
>>
>>John
>
>I tried this on Rebel 10 but it stuck to Bxa7 even after an hour (K6-233).
>I'm glad someone posted there results on this one as I think code for this
>is essential. Will the code also prevent taking such a pawn when it is the
>right choice? Or is it a type of code/knowledge that plays the odds?

Zarkov just looks at whether the bishop on a7 (or b8) is blocked by a
pawn at b6 (or c7) and where the blocking pawn cannot be immediately
captured via an exchange sequence.  If so, it is given a big penalty
since it can probably eventually be captured, or it will hang around
uselessly.  There are probably positions where this heuristic fails,
but overall I think it helps more than it hurts.

John



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