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Subject: Re: Bug in Fritz 8

Author: Bob Durrett

Date: 06:58:28 12/31/02

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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.

>
>Uri



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