Author: James Robertson
Date: 11:16:26 04/20/00
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On April 20, 2000 at 11:58:55, KarinsDad wrote: >On April 20, 2000 at 04:21:58, James Robertson wrote: > >>What is the current minumum number of bits required to store a chess position? >>If somebody could send me instructions on how to encode a chess position in as >>few bits as possible, I would be very happy. >> >>Thanks, >>James >>jrobertson@newmail.net > > >I think the answer is around 155 or so bits with a enumeration algorithm, but >I'm not sure if anyone has actually written one and proved it. The reason is >that it would be a bit of a bear to write (but doable). > >My best is 162 bits with the algorithm I put together. It also has not been >written. However, it would be quicker to calculate than an enumeration >algorithm. > >A good algorithm is the one used in EDP. It requires 192 bits, but is extremely >simple to code up. Something like: > > 64 64 bits bitboard >128 4 bits per piece times 32 pieces > >With 16 possibilites for the 4 bits, you can store the 12 standard pieces, an ep >pawn (color is known based on position), a castling rook (color is known based >on position), and a side to move king of each color, total 16 piece types. In >fact, this can be reduced to 15 piece types since you could have 3 king pieces >instead of 4; white king, black king, side to move king. > >KarinsDad :) Thanks very much for you post. I saved a copy of it for future reference. :) James
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