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Subject: Re: It is impossible to represent board position by 100 bits

Author: blass uri

Date: 00:18:45 05/22/99

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On May 21, 1999 at 21:11:44, Dann Corbit wrote:

>On May 21, 1999 at 20:49:02, blass uri wrote:
>
>>I think that even representing positions when
>>there are 32 pieces on the board is impossible by 100 bits.
>>
>>we have 15^8 options for the pawns.
>>15 options  in every file(choosing the pawns in a file is chossing 2 squares out
>>of 6)
>I don't think so.  Consider only 7 pawns of each color:
>4k3/Pp6/Pp6/Pp6/Pp6/Pp6/Pp6/4K3 w - -
>It looks legal, but can it happen?  I say no.  Arrangement of pieces is not as
>simple as throwing them on the board to see where they land.  The position must
>be possible in a game somehow.

It is illegal position because white must capture 15 pieces to go for this
position
I did  not say that throwing pieces on the board is usually legal.

I only say that probably more than 1/10 of the positions with the following
conditions are legal:

The conditions:
a)all the 32 original pieces are on the board
b) in every file there are exactly 2 pawns(white pawn and black pawn) when only
one order between them is possible(it is clear that one order is illegal if
there are 32 pieces in the board).
c)the white bishops are in squares with different colours and the same for black
bishops.

The result is that probably the number of the legal positions is bigger than
(2^104)/10 and I believe that positions with 32 pieces are only minority of the
possible legal positions

Uri



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