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Subject: Re: Question about Bit storage

Author: Vincent Diepeveen

Date: 15:44:15 01/28/02

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On January 28, 2002 at 18:17:11, Dann Corbit wrote:

that only shows how to store KRK as far as i see Dann,
not a random position with nearly all pieces on the board.

Not a single example of a full board position is inside the document.

please encode next position for me, ignore castling rights doing it:

nr3qrk/2QRp1Np/2p1Pp1n/2Pp3P/pp1P1K1P/3B1P2/PP1BNbp1/R7 w - - 0 1

>On January 28, 2002 at 18:09:53, Vincent Diepeveen wrote:
>
>>On January 28, 2002 at 18:03:03, Les Fernandez wrote:
>>
>>>On January 28, 2002 at 17:55:24, Scott Gasch wrote:
>>>
>>>>On January 28, 2002 at 17:48:48, Les Fernandez wrote:
>>>>
>>>>>Just curious to know what is the best being done now for storing a chess
>>>>>position.  In the worse case scenario (castling right exists) it takes me 162
>>>>>bits to store 32 pieces, color, location, side to move, castling, enpassant,
>>>>>promotion, ce and pv.  Now if castling rights do not exist then the worse case
>>>>>scenario for the above is 81 bits.  Much further reduction in bits/position is
>>>>>possible but at the moment I am interested in the above.
>>>>>
>>>>>Thanks in advance,
>>>>>
>>>>>Les
>>>>
>>>>How can you have a 162 bit requirement with castling rights and a 81 bit
>>>>requirement without castling rights?  You're telling me you need 81 bits to
>>>>store castling information?  Here's a breakthrough for you:
>>>>
>>>>0000 = no castling possible
>>>>0001 = white can castle short
>>>>0010 = white can castle long
>>>>0100 = black can castle short
>>>>1000 = black can castle long
>>>>1111 = all castling possible
>>>>
>>>>Scott
>>>
>>>I am aware of how many bits you need for castling.  I did not say I needed 81
>>>bits for castling I merely said that in positions that have no castling rights
>>>that I need only 81 bits to store the position.  Before you challenge my bits
>>>needed to store castling rights you might be more interested to know how does
>>>one store the entire position using only 81 bits <S>.
>>>
>>>Thanks
>>
>>please explain how to store the position in 81 bits when castling doesn't
>>matter.
>
>See this word document, referenced below:
>As Professor Clouseau once said, "And the mystery, she is solved":
>ftp://cap.connx.com/pub/les/cp.doc
>
>It's a word document.  Might get some revisions in the near future, but it
>explains it well enough.
>
>Here's another breakthrough which will reduce the 162 bits back to 81:
>Have 6 files, one for each castling status.  Then, you need no bits, because the
>castling status is implicit by the file type.



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