Author: Mike S.
Date: 18:57:05 12/01/01
Go up one level in this thread
On December 01, 2001 at 20:10:09, James T. Walker wrote: >On December 01, 2001 at 18:47:10, Russell Reagan wrote: > >>On December 01, 2001 at 16:35:31, Mike S. wrote: >> >>>(...) >>>I'm aware most people will say "use all 5 men tbs", but large experiments have >>>been made showing that the slowdown effect and other effects from using the tbs, >>>often result in *worse* performances in practical positions, than without the >>>tbs. Misjudgement of continuations which keep the game out of tbs material, is >>>one of these effects, which i.e. can make the win unecessarily easy for the >>>opponent (which may - without tbs - fail to win if the best defense in played). >>>(...) >>(...) I don't see how this >>slows down anything, unless you're talking about incorporating probing the >>tablebases into your search and evaluation of many positions. I hope someone >>will explain this to me, because I've never implemented tablebases into my own >>program and I plan to eventually, so I'm sure this will be something I'll need >>to know eventually. Yes, I meant using them in the search (much) before a tbs situation is actually reached in the game. Btw. in conjunction to that, I mentioned in earlier discussions M-Chess Pro's ability to configure *two types* of endgame table directories: One which is accessed during the search, and another one which is only accessed when the endgame material is on the board already. M-Chess didn't use the Nalimovs yet, but I think because of the doubts expressed in my 1st posting, it would make sense now too. Because now if I leave most 5 piece tbs away, they are always left away... I don't recall any replies though - people are either not interested in too much detail regarding the tbs, or underestimate the possible downside when using everything "as is". >Most all programs are probing the tablebases at the leafs. This slows some down >to about half the normal K/nps. Some like Shredder slow down to 10% of normal >(In some positions) but the ply depth is greater because of the information >obtained from the tablebases. >By the way, I had a position today where one program with tablebases had one >queen and announced mate on itself. The other program had two queens but >without tablebases only managed a draw. This is a drastic example. If resigning was on, the program with the single queen has wasted half a point... but that doesn't mean here, it played moves worse than without tablebases. From the experiment I mentioned, this was the position (NET#10) with the most unexpected results. Seven different programs played the position twice against themselves, but only one side each used the 5 piece tbs. With one exception, White *with* the tablebases lost always while *without* the tbs, White could most always draw. [D]3R4/1p6/2b5/2P1k2p/p3p2P/P6r/1P2KB2/8 b - - 0 1 "No TBS" vs. "TBS": 9.5 - 4.5 So, what (sub-)set of the tablebases is most recommendable? I'm sure programmers will have an opinion built on their own comprehensive testing. Furthermore, what do you thing about the configuration idea M-Chess Pro did use (differents directories for dynamic/static access)? Is there any other program, or GUI, which uses this idea? Regards, M.Scheidl
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