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Subject: Re: Interesting king security position

Author: Roland Pfister

Date: 23:24:50 05/24/98

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On May 21, 1998 at 12:42:13, Ernst A. Heinz wrote:

>On May 20, 1998 at 06:58:47, Roland Pfister wrote:
>
>>Watcom-Patzer on K6-233 DOS Window under WinNT 4.0 (16 MB Hash ?)
>>
>>It.5  0:02  -M7   Bxa8
>>       0:03  3.35  Ne5
>>It.6  0:06  3.70  g4
>>It.7  0:22  3.62  g4
>>It.8  2:01  3.12  b6
>>It.9  3:28  3.46  g4
>>
>>That is the version with lazy evaluation window = 130 ( = two pawns ).
>>Djordje, if you want to reproduce it, set the variable "poswin" to 130.
>>
>>The previous version that had a lazy eval window of 96 (1.5 pawns)
>>needs very long to see that Bxa8 looses. So a minor change produces
>>very different results.
>
>Really strange ... but anyway, how does "Patzer" see the mate
>(if it really is one, I am still not sure) so quickly?
>
>Do you use singular extensions or something else special?

No

>
>Or is it maybe a bug in "Patzer" that makes it solve this very
>position extremely fast?
>

You are right. I do some forward pruning that usually gets corrected
by deeper searches if it prunes wrong. But if falsely results in a
negative
mate value it will never be corrected :-(

So Patzer pruned Bxa8 and had luck because it is a bad move. If it
would have been a good move it would be desastrous...

>=Ernst=



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