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Subject: Re: little study too difficult for some programs?

Author: Gerhard Vetter

Date: 06:59:56 03/09/00

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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



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