Author: Christophe Theron
Date: 22:56:58 04/07/98
Go up one level in this thread
On April 06, 1998 at 09:49:25, blass uri wrote:
>
>On April 06, 1998 at 05:33:45, Sylvain Renard wrote:
>
>>
>>On April 06, 1998 at 03:35:06, Roland Pfister wrote:
>>>Patzer found Qe3 in 3:08 but it thinks it is a mate in 15 :-(
>>>I thought I had found that bug...
>> Capture plays Qe3 very quickly and see mate in 9 in less than
>>2 minutes (P PRO 200 MHz). The bug of Fritz 5 is vey strange,
>>someone as an idea of its origine?
>> Sylvain
>
>The evaluation function of fritz5 was:
>6.09 9/18
> 5.78 10/20
> 5.47 11/22
> 5.16 12/25
> 4.84 13/25
>4.53 14/28
>4.22 15/30
>3.91 16/32
>3.59 17/34
>3.28 18/36
>2.97 19/38
>I think this is something like 9-0.31*d when d is the depth of bruth
>force
>maybe fritz5 do some average between its evaluation by brute force
>and the eveluation of not brute force and use the depth.
>fritz4 and fritz3 have similiar bug fritz3 go almost to 0 but then go
>back
>in depth 16 it's evaluation is 0.13 and in depth 17 is 0.44 (in depth 15
>0.44
>and in depth 14 0.75)
I think it's a zugzwang problem. I don't know exactly why, but it looks
like the black queen has to stay on the a1-h8 diagonal (or else the
white queen goes on this diagonal, check, and mate in 2), and has also
to stay on the the a file.
Or something like that. Anyway, I think black is quickly caught in
zugzwang.
Programs relying on null move like Fritz (and maybe Crafty?) have
problems with this, because a general rule in those programs is that
they don't care of zugzwang problem if the queens are on the board. This
is correct 99.99% of the time, but not in this position...
More help wanted... Can somebody prove that black is in zugzwang in some
important variant of this position?
Christophe
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