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Subject: Re: So is this a BUG in Fritz 7b?

Author: Roy Eassa

Date: 12:26:40 01/31/02

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On January 31, 2002 at 15:19:16, Uri Blass wrote:

>On January 31, 2002 at 12:41:11, Roy Eassa wrote:
>>On January 30, 2002 at 18:52:06, Vincent Lejeune wrote:
>>>On January 30, 2002 at 18:07:38, Chessfun wrote:
>>>>On January 30, 2002 at 17:18:21, Roy Eassa wrote:
>>>>>On January 29, 2002 at 16:13:45, Roy Eassa wrote:
>>>>>>in the following position Black can play ...Re6 and be in
>>>>>>very good shape (certainly not behind).  However, Fritz 7b evaluates this
>>>>>>position as being better for White by about 5 pawns:
>>>>>>[d] 8/8/1p1r1k2/p1pRN1p1/P3K1P1/1P6/8/8 b - - 0 2
>>>>>Re: So is this a BUG in Fritz 7b -- something that should be fixed?  Something
>>>>>that could easily be fixed without negatively impacting anything else to any
>>>>>measurable degree?
>>>>Not just Fritz 7b, infact most Fritz versions see white clearly winning.
>>>Yes, simply because :
>>>1)white is in zugzwang
>>>2)Fritz use null-move
>>>and both are not compatible with each other.
>>But other programmers' engines use null move and they do NOT have the same
>>problem with this position (due to refinements in their null move handling, as I
>>understand it).
>>Thus this is essentially a Fritz BUG that can be fixed, thereby making Fritz
>>stronger (IMO).
>No it is not.
>It is a design decision of the Fritz programmers to use slightly different null
>move algorithm.
>many of the other programs also blunder before this move and Crafty blundered in
>the game because of it's null move algorithm.

I have never seen a position where a move immediately wins a piece and changes
the evaluation from -5 to +1, yet a top program cannot see it.

Until now.

That should be classified as a bug, IMHO.

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