Author: Robert Hyatt
Date: 13:08:52 02/13/02
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On February 13, 2002 at 15:29:32, Russell Reagan wrote: >Today in unix class after the test I had to sit there for about an hour, so I >started thinking about computer chess. I was thinking about how you would store >positions in an endgame tablebase. Here's what I came up with, and it's >drastically more than the tablebases I downloaded on to my computer. > >This is all rough estimates, but it's still nowhere close to the actual file >size of the actual TB's. I thought, 64 squares for one king, 63 squares left for >a rook, and 42 squares left for the opposing king due to 8 squares attacked by >the other king, and 14 squares attacked by the rook. That should give us (64 x >63 x 42) 169,344 positions. I tried to use as few bits as possible, so I went >with 6 bits for each index of each piece, for 18 bits. 18 bits x 169,344 >positions = 3,048,192 bits. 3,048,192 / 8 = 381,024 bytes. Divide by 8 again for >mirrored positions and rotations, and get 47,628 bytes. I haven't even included >the distance to mate values and we're at about 46 KB. The actual size of one of >the king + rook vs. king endgame TB is about 7 KB. > >So what am I missing? Are the TB as I have them on my computer in a compressed >format? > >Thanks, >Russell data compression applied _after_ the above is completed. :) lots of draws where the rook is lost, lots of duplicate mate scores, etc.
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