Author: Vincent Diepeveen
Date: 05:58:25 01/30/02
Go up one level in this thread
On January 30, 2002 at 04:57:47, Uri Blass wrote: >On January 30, 2002 at 01:56:33, Dann Corbit wrote: > >>On January 30, 2002 at 00:03:19, Robert Hyatt wrote: >>>On January 29, 2002 at 13:58:20, Dann Corbit wrote: >>>>No. His notion is that if you mirror using every symmetry, the total number of >>>>those positions (including ALL reflections) would be less than 2^81 in that >>>>category. >>> >>>OK. You are a math guy. If you allow for 8 symmetries, which is false for >>>positions with pawns, you reduce the number of bits by a factor of 8, which >>>is 3 bits. That is the mistake that is being made here, unless I misunderstand >>>something seriously. IE for king vs king, allowing _all_ possible permutations >>>even with two kings on one square, you get 64^2 positions, which is >>>2^12. If you take into account 8 symmetries, you reduce that to 2^9 positions, >>>not 2^(12/8)... >> >>Let's suppose that you need 170 bits to encode a chess position. Now, with that >>position [for instance], you may have automatically stored 50 permutation of it. >> The net number of bits needed to store each of those 50 positions is 170/50 = >>3.4 bits. > >you said >those positions (including ALL reflections) would be less than 2^81 in that >category. > >Based on the same wrong logic in this case you can say that >those positions(including ALL reflections) would be less than 2^3.4 in that >category. > >It is clearly wrong. > > > > ><snipped> >>>How can there be more than 8 "reflections"? you can find symmetry along thhe >>>vertical center, horizontal center, and the two diagonals. >> >>Well, they are actually more than just reflections. > >They are not the same position and I do not see how the fact that there are a >lot of positions that you can get the same position from them help you >practically to generate smaller tablebases. > >I am sure that it may be possible to compress the data of tablebases but the >information does not tell me how to do it. >Uri In fact these guys will never be able to generate an EGTB themselves, something real simple they invent new terms for and conclude that chess is just 2^81 + 2^3.5 positions, so before they can generate a 5 men themselves they will need to work for another 100 years and also will invent that you can reduce many positions by removing illegal positions. That will be named of course 'cutting the universe' then, not removing simply removing illegal positions as we all call it :)
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