Author: James T. Walker
Date: 19:26:16 04/24/02
Go up one level in this thread
On April 24, 2002 at 18:42:07, Russell Reagan wrote: >On April 24, 2002 at 18:37:40, Dann Corbit wrote: > >>On April 24, 2002 at 18:18:08, Eduard Nemeth wrote: >> >>>I played on the fritzserver a game comp.- comp. and in this position >>>I seen, that the Tablebases here shaw only draw-move for white with Bd7! >>> >>>I'm not sure that all Grandmasters this move woult plays? >>> >>>(german: Ich bin mir nicht sicher dass alle Grossmeister disesen Zug sehen >>>wuerden) >>> >>>[D]8/5k2/2B5/8/6pK/8/8/6r1 w - - 0 0 >>> >>>TBs says: Bd7 is only dwaw move Kg5 is a mate in 37 moves :) >> >>Not convincing. Play 1000 games of some program with tablebase files against >>the same program without. The tablebase provides perfect accuracy, but slows >>down the search. Les Fernandez did a long experiment and found that the result >>was a push -- neither stronger nor weaker. Of course that was for the program >>crafty only, so your actual mileage may vary. >> >>On the other hand, tablebase files do make programs play much prettier chess. >>And they may help weak programs a lot (if they can make it that far). > >I've never understood why this would slow down the search. Either you have few >enough pieces left to do a TB probe, in which case you do so and retrive a >perfect evaluation and your search is over, or you don't have few enough pieces >so you don't probe. It seems the only "overhead" is a single test to see if >there are few enough pieces left on the board. What am I missing here? > >Russell Hello Russell, I'm not a programmer so I may be wrong. The modern programs are probing the tablebases at the "leafs" of the search. This means they may be probing tablebases when there are as many as 15 men on the board but at the leaf they are down to 5 and tablebases are then probed. However this seems to slow down the NPS but I have seen many cases where in spite of this fact the search reaches more plies because of the info returned from the tablebases. I posted one such position a few months ago. Jim
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