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Subject: Re: An idea for saving space in tablebases

Author: blass uri

Date: 05:54:02 10/09/98

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On October 09, 1998 at 08:10:51, blass uri wrote:

>I think it is better to store the number of moves to win in the tablebases only
>if this number is divisible by 2 because otherwise you can compute the number of
>moves by search.
>
>Maybe it is possible practically to store it only if it is divisble by 3 or 4 (I
>do not know what is the speed of reading the tablebases from harddisk)
>
>Uri
I think it is easy to save at least 1 bit per position by this idea if in
positions when there is win in N when N is divisible by 2 you store win in N/2
and in positions when there is a win in N when N is not divisible by 2 you store
a win in 1(you can discover by search that it is not truth).

By this idea you can use the same number of bits to every position.

If you want to use different number of bits to every popsition you must add 1
bit
to tell if the is a position with win in number of moves divisible by 2 or not.

of course if you lose it is not important to know the number of moves.

I use the word win and not mate because it is a mistake to use mate
because of the 50 move rule

Uri



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