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Subject: Re: It's a DRAW !

Author: Dieter Buerssner

Date: 11:17:34 05/12/05

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On May 12, 2005 at 09:23:13, Uri Blass wrote:

>On May 12, 2005 at 09:00:31, Ross Boyd wrote:
>
>>On May 12, 2005 at 07:55:03, James T. Walker wrote:
>>
>>>As soon as either white pawn is captured, 6 man tablebases will tell you it's a
>>>draw.
>>
>>Amazing. A Draw?????!!!!!!
>>
>>Thanks for pointing this out. It doesn't look possible, but I believe you.
>>I wonder how many engines see the draw without 6 men EGTBs?
>>
>>Cheers,
>>
>>Ross
>
>Yace cannot even after capturing the pawn
>I delete most of the analysis and a question to Dieter is how is it possible
>that the selective depth 110 is smaller than the depth 126.

This is easy to answer. All paths in the search tree end, before the depth is
reached. Reasons are: stalemate, mate, repetition, 50 moves rule, cutoff from
TT.

>Note that Yace can see the draw easily one ply later without learning at depth
>54/109.
>
>It suggest that there is some bug in yace,

Possible. Perhaps I am going to investigate this by a tree dump. I guess, it has
to do with the fact, that TTs handle repetion and 50 moves rule wrong. Often,
this is "self healing" with higher depths. But not in this case. I thought I had
some code, to not proble HTs when remaining depth + half move counter without
capture/pawn move > 100. Perhaps I have taken out this code again ... Even with
this code, the result will not be reliable. But it may reinforce the self
healing.

Regards,
Dieter



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