Author: James Robertson
Date: 09:07:41 03/09/00
Go up one level in this thread
On March 09, 2000 at 09:59:56, Gerhard Vetter wrote: >On March 08, 2000 at 19:07:36, James Robertson wrote: > >>On March 08, 2000 at 18:34:44, Gerhard Vetter wrote: >> >>>On March 08, 2000 at 18:26:44, José de Jesús García Ruvalcaba wrote: >>> >>>>On March 08, 2000 at 18:04:48, Andrew Dados wrote: >>>> >>>>>On March 08, 2000 at 17:54:35, Gerhard Vetter wrote: >>>>> >>>>>>Lately I found this easy-to-solve but elegant little study: >>>>>> >>>>>> >>>>>>8/8/8/8/4k3/1P1p4/1r6/R1N1K3 w Q - >>>>>> >>>>>>To my surprise many modern programs can't find the win despite of 5manTBS only >>>>>>2ply away! >>>>>> >>>>>>Junior 6 (with 5manTBS) sees only a draw after 45 min on Celeron 500/ 128 >>>>>>Also Shredder 4 and Nimzo 7.32 fail to solve it. >>>>>> >>>>>>It is interesting that the older versions of some of the above programs need >>>>>>only 0 sec >>>>>>(Nimzo99) resp. 10 sec (Junior 5.0). Tiger 12.0e takes also 0 sec. >>>>>> >>>>>>It would be interesting to know how other programs do in this position and even >>>>>>more >>>>>>interesting if someone can suggest a reason for this odd behaviour of some >>>>>>leading programs. >>>>>> >>>>>>Since I don't know if this information is embedded in the EPD: white has still >>>>>>castling rights. >>>>>> >>>>>>Gerhard >>>>> >>>> >>>> Yes, the queenside castling rights are in the fen string you posted (it is the >>>>'Q' after the side to move). >>>> >>>>>I can be that your tablebases are somehow broken.. note that all programs >>>>>without TB access solved it... >>>>>It's of course just a guess. >>>>> >>>>>-Andrew- >>>> >>>> The very simple explanation is that Nalimov tablebases do not store castling >>>>rights. >>>>José. >>> >>>sounds like a sensible reason, but why can Fritz 6 solve it then (with >>>tablebases activated)? >>>Gerhard >> >>Because Fritz only uses the tablebases if the current position is in the >>tablebases (since it uses tablebases stored on the CD, it would be too slow to >>use them in the search). >> >>James > >thanks for everybody's input, what I learned that in some endgame positions one >better not uses tablebases access because the implementation is still buggy. >Gerhard The only bugs I have found in the Nalimov tablebase implementation have been my own. :\ It was a decision to not store castling rights that Eugene made, so we can't really call it a bug.... James
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