Author: blass uri
Date: 05:06:58 04/24/00
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On April 24, 2000 at 08:00:45, blass uri wrote: >On April 24, 2000 at 06:57:50, Victor Zakharov wrote: > >>Theoretical calculations are very rough. Chess Assistant has algorithms of >>variable length board compression (so called Direct tree). Results are >>impressive. Average size is 12 bytes per position in Chess Assistant 4.0 and 11 >>bytes in CA 5.0. And speed is good engough too. Two interesting observations: >>there are a few positions that are packed in 56 bits (i.e. less than 64 bits and >>less than one bit per a square!), and there are no positions packed more than 19 >>bytes (144 bits). > >I believe that it is impossible because there are probably more than 2^144 legal >positions. > >Uri I can add that my program worked hard to calculate an upper bound to the number of legal positions and it only could prove that something like 2^156 is an upper bound. I do not believe that chess assistant can compress every chess position with less than 145 bits. There is probably a misunderstanding. Maybe it only compress part of the legal positions(for example legal positions with no promoted pieces and 32 pieces) Uri
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