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Subject: Re: Bitbases for all! -> TB's ?? and move lists

Author: Joshua Shriver

Date: 12:17:03 11/22/05

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Nice, by chance know where they can be downloaded? Are there different BB
formats? Are there any open-source generators?

-Josh


>
>You just try all child positions and choose the one with the smallest DTM.
>
>The advantages of bitbases is that they are MUCH smaller.  First, many 6-men
>tables have DTMs > 127, which means they need two full bytes per position.
>Bitbases need only 0.25 bytes.  Secondly, bitbases compress MUCH better.  This
>is easy to see, as a tablebase will look like this:
>
>+11 +9 +25 +4 0 +9 +7  -> mostly wins, but all with different distances
>
>as compared to a bitbase
>
>11 11 11 11 01 11 11    -> and all the wins can be compressed very neatly using
>run-length/Huffman etc.  Furthermore all the wins will tend to lie together if
>you order your indexing right.
>
>The complete set of 6-man Nalimov TBs are >= 2TB I think, whereas I think
>Vincent said his Diep bitbases were 100GB or something like that.
>
>anthony



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