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Subject: Re: compressed Nalimov tablebases??

Author: Dann Corbit

Date: 17:49:19 11/09/01

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On November 09, 2001 at 18:55:53, Bruce Moreland wrote:

>On November 09, 2001 at 16:15:12, Bernardo Wesler wrote:
>
>>Is there any website from where i can download compressed or zipped nalimov
>>tablebases, 3, 4 and 5 ?
>>Thanks.
>
>If you are trying to get them to download faster by finding a place zipped
>versions, compressing the Nalimov tables is like trying to compress a bucket of
>sand.  It doesn't work.
>
>Compression schemes work by finding order in data and removing it.  Perfectly
>compressed data has no order in it, so it can't be compressed.  The Nalimov
>files are very well compressed.

There are two formats for the Nalimov endgame tablebase files.  The generators
make decompressed tablebase files, which are enormously huge.  The files on Dr.
Hyatt's FTP site have already been compressed with Andrew Kadtech's compression
algorithm.  This makes them much smaller.  Of course, since they are already
compressed, there is precious little entropy left to squeeze out of them, so
further compression attempts are a waste of time.  Since the generators are
available in binary and source code form, there may also be sites which have
decompressed Nalimov tablebase files here or there.  In any case, it would be a
big mistake to download those if you found them somewhere.



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