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Subject: Re: 6-man TBs

Author: Robert Hyatt

Date: 08:43:53 02/02/05

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On February 02, 2005 at 05:32:00, George Tsavdaris wrote:

>On February 02, 2005 at 01:06:30, Robert Hyatt wrote:
>
>>On February 01, 2005 at 21:39:40, Anthony Cozzie wrote:
>>
>>>Is there any chance of some 6-man tables becoming available before CCT?  My wish
>>>list is actually pretty small:
>>>
>>>KRPKRP (only the white-side is available from Bob right now?)
>>
>>think about it.  If pieces are symmetric you only need one side.  Just turn your
>>white pieces into black ones, and the black ones into white ones, and look it
>>up.  :)
>
> Actually, this is what i thought the first time i saw there are tablebases for
>white and for black, for the same endgame(KRPKP for example). So i thought they
>would have the exact same size. But no, this isn't happening.
>For example KBBKNBB.EMD is 200 KB, while KBBKNBW.EMD is 243 KB.
>Can you explain why..........????????? It seems very bizarre to me!?!?!?!?!

Yes.  Give a position for white to move with white having more material.  Then
same position with black to move.  If it is a mutual-zugzwang position, one can
have a long winning path, while the other has a short drawing path...

Positions with more draws compress better as there are more zero values in the
file.  Positions leading to mate have lots of n, n-1, n-2, n-3, etc type mate
scores which don't compress very well.  The tables have to contain a pretty
fixed number of positions, but the larger the table, the more mates there are.
A KK table would be just a few bytes long, for example.  All scores would be 0
and that would compress like crazy. :)


>
>>
>>
>>>KRPPKR
>>>KQPKQP
>>>KQPPKQ
>>>KRKPPP
>>>KNPPKR
>>>KBPPKR
>>>KBPKNP
>>>KRPPKQ
>>>
>>>There are a few others that I wouldn't mind having, but those are the really
>>>useful ones that come to mind.  I guess the above would total 30GB or so, which
>>>is a fair bit but not completely outrageous.
>>>
>>>anthony



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