Author: Angrim
Date: 03:37:20 11/13/99
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On November 13, 1999 at 03:52:43, Alexander Kure wrote: >On November 12, 1999 at 20:24:29, James Robertson wrote: > >>I was wondering if it is a good idea to probe the tablebases in the qsearch. Is >>this a smart thing to do? >> >>James > >This is exactly what Nimzo 7.32 already does. All 3 and 4 piece endings have >been converted from Nalimov into a special format (NCD - Nimzo compressed data), >where only the information of win, draw or loosing for each position is stored >(needs only 2 bits per position). At startup these endings are loaded into >memory (requiring app. 11 MB for all 3 and 4 piece egtbs) and probed in the >q-search, which is faster than calling the evaluation function! 2 bits per position is still more than you need since there are only 3 values possible. Useing base 3 you can store 5 entries per byte instead of just 4, saveing 20% on memory. This can be probed just as fast as the 2 bits per entry method since you can still directly calculate which byte of the table contains each entry. To extract entry N read byte index N/5 and extract the (N mod 5)+1st trinary digit from this byte. Where the first digit is N mod 3, the second is (N/3) mod 3, third is (N/9) mod 3, etc. Hope this is helpful, Angrim
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