Author: Aaron Tay
Date: 09:10:07 12/02/01
Go up one level in this thread
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
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