Author: Uri Blass
Date: 02:34:57 04/22/03
Go up one level in this thread
On April 22, 2003 at 04:30:14, Sune Fischer wrote: >On April 22, 2003 at 04:14:44, Uri Blass wrote: > >>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? >> >>I think that it is related to the knowledge that frenzee and Ruffian has and >>ankadota and movei have not. >>Movei does not use tablebases so it plays the right move but >>Movei has a negative score for white after Ra4+ even after a long time and I >>hope that it will be changed after adding score of pawns relative to kings. > >Frenzee doesn't have any knowledge of this, but it also chooses the wrong move >Ra4+, and so does Yace btw. It's a little strange that they both show a draw >score for a non-drawing move, apparently they are content with a draw, so I'm >not sure why they don't chose Rxh4 immediatly. >Ruffian must have special knowledge so it is a bad example, it shows a draw >score from ply 1 :) I do not know. Does Ruffian show scores at ply 1 or 2? I never saw them. can you post analysis of Ruffian at depth 1 or 2? Uri
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