Author: Drexel,Michael
Date: 01:20:21 04/22/03
Go up one level in this thread
On April 22, 2003 at 03:13:41, Sune Fischer wrote: >On April 21, 2003 at 18:24:45, Drexel,Michael wrote: > >>On April 21, 2003 at 18:09:03, Uri Blass wrote: >> >>>On April 21, 2003 at 17:18:46, Robin Smith wrote: >>> >>>>On April 20, 2003 at 17:20:11, Uri Blass wrote: >>>> >>>>>It may be possible to use it in a productive way to avoid problems >>>>>that I mentioned(the program prefers loss by KR vs KPPP and not drawn KR vs KPP) >>>>>by having rules to trust tablebases scores only in part of the cases but I do >>>>>not like it. >>>> >>>>Uri, >>>> >>>>I know such things are possible in theory. Can you give an example of it >>>>actually happening? >>>> >>>>Robin >>> >>>No >>>If I remember correctly I saw a case when it happened but >>>I did not care to save the position and I do not plan >>>to look for it now. >>> >>>Uri >> >>[D] 8/8/8/7P/4K1P1/r6P/k7/8 b - - 0 1 >> >> >>Anaconda 1.0 lost this position with tablebases. >>It would take the pawn without. > >It's a fluke. > >I think what happens here is that table bases tell the engine it has a draw if >it wants it, however the engine is "stupid" and believes it is better and will >not be satisfied with a draw. > >So it's a simple horizon problem as far as I can tell, the TBs provide >"infinite" depth but the engine does not like the truth it sees and prefers to >kid itself. Without TBs it doesn't know it choosing a drawing line, so it >happily eats the pawn. > >If the engine was a little better it would know the draw was the best option >anyway. I don't know about Anaconda, but Ruffian and Frenzee both get a draw >score showing pretty fast with TBs, so maybe this is related to a bug in >Anaconda? IIRC Yace Paderborn would make the mistake Ra4+ on my AMD at home too. Crafty likes Rc3 here which seems to be still a draw. Michael > >Certainly to conclude from an example where "stupidity by random luck is bliss", >that table bases hurt, must be considered rediculous. > >-S. > >>Michael
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