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Subject: Re: here it is: a mate in 8

Author: Heiner Marxen

Date: 05:02:41 01/19/01

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On January 19, 2001 at 07:54:21, leonid wrote:

>On January 19, 2001 at 06:34:32, Heiner Marxen wrote:
>
>>>Only one thing I see as practical why saving the moves that lead
>>>to given position, is the taken of pawn "en passant". There you need "previous"
>>>move to know if it pawn should be taken.
>>
>>Ah, I see.
>>But I would not store a cemplete last move, but rather, if and into which
>>column an e.p. may happen just now. That takes 4 bit (9 cases).
>>I have also 4 bits for the castling rights, and one bit for the side to move.
>>Total: 64*4 bit square contents, 4+4+1 Bit extra info.
>
>Interesting to see that you do this some other possible way. Actually rocks with
>all the details about this (where rock already happened, what king or rook ever
>changed its initial place and some other data) is kept in one variable. 2 bytes.
>Previous move program keep in 4 bytes long variable as every move. This I do
>probably because I could not see other way but mainly for simplicity. Even
>description of the board I keep in exact 64 bytes chain. It could be reduced to
>much less volume but then the simplicity will vanish.
>
>Leonid.

Ah, yes, sure.  I was not very clear.

I use this compact coding (4 bit for each square etc) only for the TT.
Otherwise Chest uses quite a different format.

Yes, simplicity is a good thing.

Heiner



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