Author: Russell Reagan
Date: 12:29:32 02/13/02
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
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