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Subject: Re: Difficult position for programs, at least for Crafty.

Author: Robert Hyatt

Date: 09:00:07 08/10/99

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On August 10, 1999 at 10:44:49, Bernhard Bauer wrote:

>On August 10, 1999 at 10:24:30, Robert Hyatt wrote:
>
>>On August 10, 1999 at 02:25:56, Bernhard Bauer wrote:
>>
>>>On August 09, 1999 at 12:24:56, Robert Hyatt wrote:
>>>
>>>>On August 09, 1999 at 10:02:42, Bernhard Bauer wrote:
>>>>
>>>>>Hallo,
>>>>>
>>>>>recently I came across a position from a game
>>>>>Haenninnen - Szabo, Wageningen.
>>>>>
>>>>>The position is
>>>>>FEN: 3r1rk/pp1q2b/3p2pp/PP1Np2n/2Pp1p/B2P2Pb/3QPPBP/R4RK w
>>>>>
>>>>>The game went on
>>>>>19. Bxd6 Bxg2
>>>>>20. Bxf8 Qh3
>>>>>21. Bxg7 f3
>>>>>22. exf3 Bxf3
>>>>>23. Ne3  Kg7
>>>>>24. Qb4  Rd7
>>>>>25. Ra2  Nf6
>>>>>White resigned.
>>>>>
>>>>>Programs have difficulties to find out that 19. Bxd6 is bad.
>>>>>The whole line seems to be difficult at least for Crafty.
>>>>>BTW Crafty produces a lot of debug messages on a Sun, not on a PC.
>>>>>
>>>>>Enjoy
>>>>>Bernhard
>>>>
>>>>
>>>>What is "a lot of debug messages"?  If you are getting oddball error messages
>>>>then something is definitely wrong...
>>>>
>>>Messages like this:
>>>captured a king
>>>piece=5,from=51,to=44,captured=3
>>>ply=16
>>>My logfile is 5.2 Mb in size.
>>>
>>>
>>>>As far as the position goes, the end has a B on F3, Q on h3, which is a known
>>>>"null-move" killer...
>>>
>>>Oh, not known to me. But I feared it would be a null move problem again -:)
>>>Kind regards
>>>Bernhard
>>
>>
>>That is definitely bad.  Such errors should never occur, and are only present
>>to catch errors that I introduce when changing the code...  Can you post a
>>FEN for aposition that will produce such an error?
>
>Of course
>FEN: 3r1rk/pp1q2b/3p2pp/PP1Np2n/2Pp1p/B2P2Pb/3QPPBP/R4RK w
>See above.
>
>BTW the hardware is a Ultra Sparc with 2 procs.
>fpversion gives:
> A SPARC-based CPU is available.
> CPU's clock rate appears to be approximately 166.8 MHz.
> Kernel says CPU's clock rate is 168.0 MHz.
> Kernel says main memory's clock rate is 84.0 MHz.
>
> Sun-4 floating-point controller version 0 found.
> An UltraSPARC chip is available.
> FPU's frequency appears to be approximately 170.5 MHz.
>
> Use "-xtarget=ultra" code-generation option.
>
>The OS is Solaris 7 from May 99. It's the 64-bit version.
>The compiler is gcc2.95
>
>Kind regards
>Bernhard


OK.. I overlooked that this was the same position discussed earlier.  I ran this
a bunch of times with no strange output at all.  I'd guess that somehow the
optimizations are going wrong...  try compiling without the -O at all, and then
run the same test.  And keep adding optimizations back in until you do see the
error.

I ran with 1 cpu, 4 cpus, long and short search times, with none of that
'captured a king' internal diagnostic error stuff at all...



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