Author: Ricardo Gibert
Date: 23:36:01 03/03/01
Go up one level in this thread
On March 03, 2001 at 23:08:39, Robert Hyatt wrote: >On March 03, 2001 at 19:54:03, Pham Minh Tri wrote: > >>On March 03, 2001 at 10:29:40, Robert Hyatt wrote: >> >>>On March 03, 2001 at 02:44:01, Pham Minh Tri wrote: >>> >>>>Hi, >>>>Could anyone explaint to me what content of a cell of EGTB is? >>>>Thanks in advance, >>>>Pham >>> >>> >>>It is a single byte that either has a 0 (draw) or +/1 N, where N is the number I don't understand "+/1 N" even though I think I know what you mean. >>>of moves to the forced mate... >> >>Thank you very much for your answer. Could you tell me more: >>- How to index a cell in EGTB? >>- How large of EGTB of Crafty (how many entries)? >>- How to orgnize raw data (the data would be converted into EGTB)? >> >>Thanks in advance, > >1. the basic idea is that for a 4 piece ending, you take the square numbers >for the 4 pieces, which are 6 bit numbers, and simply concatenate them into >a "Godel number" that is 24 bits long. This indexes to a single byte in >the egtb. You may need to add a few bits for en passant and castling rights. > >It is more complex than this because you don't need a 24 bit number, you can >do it with a few less bits... 8-fold symmetry for pawnless endings. 4-fold symmetry for endings including pawn(s). > >all the 3-4-5 piece files for crafty take about 7.5 gigabytes of disk space. > >2. You don't organize raw data... you do a search looking for all positions >that are mate in 1, then mate in 2, etc...
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