Author: James T. Walker
Date: 09:18:45 12/02/01
Go up one level in this thread
On December 02, 2001 at 12:10:07, Aaron Tay wrote: >On December 02, 2001 at 10:04:39, James T. Walker wrote: > >>On December 01, 2001 at 21:57:05, Mike S. wrote: >> >>>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 >> >>Hello Mike, >>I'm interested in your experiment. What time control did you use for this test. > >I'm very curious as well. Why do you think the side with the tablebase lost? Due >to time wasted probing useless positions? Or did the side with tablebases resign >to early, or avoided converting to a "loss" endgame in theory, but play a even >weaker and even easier to win position? > >Your starting position is very far away from 5 men set, how many tb hits are you >getting? Do the moves vary a lot between the side with tbs and those without? > > > >>Jim I just ran this position with Chess Tiger 14.0 & Shredder 5. Both programs draw with tablebases. I find it hard to believe that any of the top programs will lose this ending with tablebases. The opposite colored bishops make this position a likely draw. Jim
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