Author: Russell Reagan
Date: 15:39:23 02/13/02
Go up one level in this thread
On February 13, 2002 at 16:08:52, Robert Hyatt wrote: >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. How is the decompression handled with the large TB's? Obviously you can't decompress a 3GB file from disk and probe it every move. Does it do partial decompression of a certain number of bytes? I'm curious how this works. Russell
This page took 0 seconds to execute
Last modified: Thu, 15 Apr 21 08:11:13 -0700
Current Computer Chess Club Forums at Talkchess. This site by Sean Mintz.