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Subject: Re: Preprocessor blues?

Author: Ernst Walet

Date: 08:46:35 02/09/00

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On February 08, 2000 at 10:19:06, Stefan Meyer-Kahlen wrote:

>On February 07, 2000 at 16:10:55, Ernst Walet wrote:
>
>>I´ve seen some strange evaluation glitch in Shredder 4 with the following
>>position.
>>
>>8/1K6/8/5k2/bR1P1r2/1n6/8/8 w - -
>>
>>Shredder wants to play Rxa4, score ply 9-14 about -1.2
>>
>>Make the move.
>>
>>Shredder wants to play Nxd4, score ply 9-14 about +4.71
>>
>>Make the move.
>>
>>Shredder wants to play Ra8, score ply 9-14 about -1.3
>>
>>
>>Why such a different score after the first move?  Does Shredder much
>>preprocessing?
>>
>>Ernst-J.
>
>
>Thanks for your interesting post!
>


You´re welcome.


>First of all, Shredder's evaluation is always from the point of view
>of the moving side, so there is "only" a difference of 3.5 pawns and not
>5 pawns :-)
>


I know, nevertheless....


>This is a special case for which I added code after Jakarta 96, where Shredder
>almost blew a game against Virtual Chess.
>
>I, like many other programmers, evaluate a KRN-KR ending very drawish. In your


You´re right, this game ended as draw.


>second example, I simple deactived that code so Shredder as black this time will
>go for the last white pawn. If the code were still active, Shredder would never
>capture the pawn, because KRN-KRP would be better than KRN-KR. I agree that
>there are other ways to solve that issue, but I haven't touched that code for
>quite a while now and almost forgot that this is still in there.
>
>I agree that this is very brute force, but that method proved to be very
>succesful in chess :-)
>
>Hope this helps
>   Stefan

Thanks for your reply, Stephan.

Ernst-J.




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