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Subject: Re: Creating Tablebases like the SETI-project.

Author: Guido

Date: 15:02:44 06/27/03

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On June 27, 2003 at 16:37:23, John Merlino wrote:

>On June 27, 2003 at 14:43:33, John Merlino wrote:
>
>>On June 27, 2003 at 08:25:28, Guido wrote:
>>
>>>On June 26, 2003 at 15:33:29, John Merlino wrote:
>>>
>>>>On June 26, 2003 at 14:12:32, Peter Stayne wrote:
>>>>
>>>>>Has anybody figured out how big a complete (w/ pawns) set of 6-mans would be.
>>>>>And noone has completely rendered these yet right?
>>>>
>>>>Marc Bourzhutsky (sp?) is currently creating 6-man files in the de Koning format
>>>>used by Chessmaster. When last I was notified of his progress (which was quite
>>>>some time ago), he had well over 30 DVDs of archived data, but had only
>>>>generated about 10% of the files. I'm pretty sure that the estimate of "over one
>>>>terabyte" is still accurate.
>>>>
>>>>Since the de Koning format tends to be about 20-25% smaller than the Nalimov
>>>>format (or at least it was with the 5-man files), you can feel free to make
>>>>assumptions if you like....
>>>>
>>>>jm
>>>
>>>Is the 20-25% reduction referred to the normal or to the compressed files?
>>>
>>>Does de Koning format contain info on win, loss and draw, or only on win and
>>>loss+draw without distinction between these last two results?
>>>
>>>Thanks
>>>Guido
>>
>>The de Koning format is always compressed. There is no uncompressed version.
>>
>>The de Koning format contains win/not-win only.
>>
>>jm
>
>I need to clarify that last statement. The ReadMe file for the de Koning
>generator program says:
>--------------
>The following table sheds some light on the relation between moves,
>plies, and side to move.
>
>data    means wtm ...       means btm ...
>---------------------------------------------
>   0    (not used)          is mated
>   1    wins in   1  ply    loses in   2  ply
>   2    wins in   3  ply    loses in   4  ply
> 253    wins in 505  ply    loses in 506  ply
> 254    wins in 507+ ply    loses in 508+ ply
> 255    draws or loses      draws or wins
>--------------
>
>jm

Thanks for explanations.
It is very interesting the idea of generating TBs already compressed.
I suppose that the 20-25% of reduction is due to the chosen format that contains
more sequence of zeroes (from an "uncompressed" point of view), if compared with
Nalimov's TBs.
The main advantage of this format seems to me avoiding of 8-16 bits problem that
will arise with 6-men TBs, paying something with the reduction in information
contained in a single file.
I also suppose that the algorithm used by FEG is based on the retrograde move,
considering the relatively very short cpu time spent in generation.

Ciao
Guido



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