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Subject: Re: Bug in Fritz 8

Author: Drexel,Michael

Date: 07:25:11 12/31/02

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On December 31, 2002 at 10:06:28, Uri Blass wrote:

>On December 31, 2002 at 09:58:28, Bob Durrett wrote:
>
>>On December 31, 2002 at 09:33:06, Uri Blass wrote:
>>
>>>On December 31, 2002 at 09:01:55, Bob Durrett wrote:
>>>
>>>>In the following position, with Black to move, Fritz 8 says the correct move is
>>>>Re8.  It gives a position evaluation of 0.00
>>>>
>>>>5r1k/pp1p2pp/n4q2/2pB4/2P2r2/8/PP2QPPP/R4RK1 b - - 0 18
>>>>wKg1,Qe2,Bd5,Ra1,f1,Pa2,b2,c4,f2,g2,h2/bKh8,Qf6,Na6,Rf4,f8,Pa7,b7,c5,d7,g7,h7
>>>>
>>>>I forgot how to display the position here.  Maybe someone will do it for me.
>>>>
>>>>Bob D.
>>>
>>>Can you post the relevant game.
>>
>>I absolutely guarantee that you don't want to see the relevant game.  It was one
>>of my 60+ blitz 2 12 ICC games which I played recently, after years of
>>inactivity, for the purpose of determining how much my game had deteriorated.
>>The game is filled with big errors on both sides.
>>
>>>
>>>Maybe Re8 force repetition of the position so Fritz prefers repetition and not
>>>negative evaluation(of course in that case white made an horrible blunder in a
>>>previous move).
>>
>>If you will look at the position, you will see that there is no chance for a
>>draw by repetition of the position.  But your idea does sound right.  Fritz must
>>have gone into a mode where it "thought" there was a repetition of the position.
>> Maybe there is an unintended jump to that "repetition of position display"
>>subroutine or function which occurs improperly sometimes.
>>
>>
>>>
>>>A lot of programs evaluates first repetition as a draw.
>>>It may be wrong in analysis but in games it is usually no problem.
>>
>>This jumped out at me in post-mortem analysis.  Strangely, my opponent in the
>>actual game also played Re8?? and I, shamefully [!!!], failed to capture the
>>rook.  Maybe this has something to do with the bug.
>
>In that case it is not a bug because most programs are designed to assume that
>second repetition is a draw in the analysis.
>
>A bug is something that the programmer did not mean to happen.
>
>I admit that there may be cases when it is not a draw but there are more
>important things to improve than this problem that is not easy to solve in a
>productive way(solutions may generate other problems like not seeing a draw by
>repetition or not trying to make progress and often repeating a previous
>position).
>
>Uri

Chessbase should know that most chessplayers are using Fritz for Analysis.
Fritz engines often used the famous X piece in analysis mode.
In my opinion Fritz engines are simply bad analysis engines.
Shredder 7 does not show 0.00 in case I repeat moves in this position.
it shows +-(9.94) Qxe8+ even if I repeat the moves 100 times.



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