Author: Robert Hyatt
Date: 20:59:48 04/07/01
Go up one level in this thread
On April 07, 2001 at 12:14:43, Uri Blass wrote: >On April 07, 2001 at 11:46:25, Rajen Gupta wrote: > >>On April 07, 2001 at 10:46:43, Uri Blass wrote: >> >>>On April 07, 2001 at 09:04:28, Rajen Gupta wrote: >>> >>>>hi; thanks for the answers: however isn't it true that the 4cd set by chess base >>>>(endgame turbo)consists of nalimov EGTB's whereby the chess engine can actually >>>>search for a position encoded within these tablebases as opposed to the ordinary >>>>ones in which only when a position that is in the EGTB,is actually reached >>>>during game play that the EGTBs kick in? >>> >>>You are wrong about your assumption about the ordinary ones. >> >>Hi uri: >>by ordinary ones i meant ordinary EGTB (the ken thompson ones)as opposed to the >>newer nalimov EGTB.i wasn't referring to a particular chess engine having the >>capacity to access them in the search.it is my understanding thqt with nalimov >>EGTB the chess engine can actually search for a position encoded within the EGTB >>as opposed to the older EGTB which kick in only when a psoition has actually >>been reached which is within the EGTB. >> >>correct me if i'm wrong > >I do not see a reason to assume that the thompson tablebases cannot be used in >the search in the same way that nalimov tablebases are used. > There is a big reason. Ken's compression algorithm is not nearly as good as what Eugene uses, from a random-probe point of view. IE with Eugene's code, a random probe doesn't have to read huge chunks of the file first, which makes probing inside the search doable. If you use the Thompson compression approach, probing would be horribly slow if done deep in the search. >The thompson tablebases did not give accurate result for part of the positions >and it gave only correct results for positions when the strongest side could win >but I see no reason that prevent chess programs to use the information in the >search. Ken also ignored enpassant, which means 2 pawns were impossible. > >I believe that the reason that Fritz could not use the thompson tablebases in >the search was the fact that the programmers were too lazy to teach fritz to do >it(they were even too lazy to tell Fritz to use the thompson tablebases >correctly at the root). > >The thompson tablebases are bigger than the nalimov tablebases and nobody use >the thompson tablebases today so this subject is not relevant. > >Uri Nalimov == smaller & more efficient to access...
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