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Subject: Re: A Weird (and Illegal) Game in Big Database '99 (not true for CBG!!)

Author: Michel Langeveld

Date: 13:52:25 09/26/99

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This is true for CBF but not for CBG!!!!! CBG uses a much more complex decoding
algoritm.

In CBG moves are stored like this.
0x00 = move 2nd queen (+6, +6) or (-2, -2)

So the byte 0x00 is used for 2 different moves. And only 1 possibility is
possible in a given position.

0x1f means 4 different moves:
     move 2nd queen (-4, -4) / (+4, -4) / (+4, +4), (-4, +4)

note:
The second queen is a promoted queen.
The second bishop is the bishop at field G the third bishop is the first
promoted bishop.

Some moves are stored in 3 bytes, like promotions.

Further more the moves are stored with the ply number incremented.

All this info has to be released on my homepage soon.

So the bytecode at ply 4 = bytecode-4.

Kind regards,

Michel Langeveld
rudolf@stad.dsl.nl
Chess Formats Page: http://stad.dsl.nl/~rudolf

On September 26, 1999 at 16:38:03, Georg v. Zimmermann wrote:

>I guess most of you know.
>The games in CB are stored this way:
>
>13 {13th legal move by white}
>12 {12th legal move by black}
>27 {27th legal move by white}
>...
>
>This is to use only one byte per move and use less space.
>Now if only one move gets mixed up ... ;)
>
>--Tec



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