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Subject: Re: Dangerously stupid tablebase idea...

Author: Andreas De Troy

Date: 15:03:35 10/19/01

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I once mentioned a +/- similar idea here, to reduce the storage requirements for
PGN-files (read: to "ZIP them more efficiently): if you agree on a certain move
generator (MG), you could store your move as the number of the move the MG
generates.

For instance, in the start position, if this move generator produces moves a3,
a4, b3, b4, ... in that sequence, move 1. a4 would be stored as the number 2
(it's the second move generated).

You don't have to count the maximum number of moves possible in any position to
determine how many bits you need; you can examine the position (generate all
possible moves) and use just as many bits as you need for that particular
position (for instance, if there are 4 legal moves, you use 2 bits; and since
you know that only 4 moves are possible, you just look at the next 2 bits in
your datafile to decode the "next move").

Disadvantage: to decode, you need to know how many moves are possible and that
takes time.

I opened this post with "I once mentioned a +/- similar idea here, ...". I will
tell you what happened then: some guy replied that this "move NUMBER"-idea was
exactly what was used in the (now old) Chessbase-format.

There it ended. But indeed -maybe a similar idea can be used in tablebases?



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