Author: Sune Fischer
Date: 00:13:41 04/22/03
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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? 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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