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Subject: Re: Crafty bugs (?)

Author: Robert Hyatt

Date: 08:12:21 08/25/98

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On August 25, 1998 at 10:41:01, Bernhard Bauer wrote:

>Ok. Here is the log file
>--------------------------------------------------------------
>Crafty v15.18 (2 cpus)
>
>max threads set to 2
>using cpu time
>hash table memory = 24M bytes.
>pawn hash table memory = 10M bytes.
>
>White(1): setboard 4k3/nnnnnnnn/8/8/8/8/RRRRRRRR/4K3/ w
>
>       +---+---+---+---+---+---+---+---+
>    8  |   |   |   |   | *K|   |   |   |
>       +---+---+---+---+---+---+---+---+
>    7  | *N| *N| *N| *N| *N| *N| *N| *N|
>       +---+---+---+---+---+---+---+---+
>    6  |   |   |   |   |   |   |   |   |
>       +---+---+---+---+---+---+---+---+
>    5  |   |   |   |   |   |   |   |   |
>       +---+---+---+---+---+---+---+---+
>    4  |   |   |   |   |   |   |   |   |
>       +---+---+---+---+---+---+---+---+
>    3  |   |   |   |   |   |   |   |   |
>       +---+---+---+---+---+---+---+---+
>    2  | R | R | R | R | R | R | R | R |
>       +---+---+---+---+---+---+---+---+
>    1  |   |   |   |   | K |   |   |   |
>       +---+---+---+---+---+---+---+---+
>         a   b   c   d   e   f   g   h
>
>White(1): d
>White(1): go
>              clearing hash tables
>--------------------------------------------------------
>


I tried that on three machines here, my linux box, a solaris box, and
an SGI.  I can't reproduce this...  are you using the same compiler (gcc)
on all your machines?  I don't have a 2.7.0 anywhere as that had bugs and
was quickly replaced by 2.7.2 and then later versions...




>>
>>>
>>>I think you should be able to reproduce this behavior - and it may be
>>>important because it you don't get this running a different gcc under
>>>LINUX you may have an error that may not show up for you, but is still
>>>there and may produce bad results in other cases.
>>>
>>
>>
>>it is equally probably that msvc has a bug..  but I need to know where the
>>program is blowing up before I can figure that out.  IE you might compile with
>>-g, then run it under the debugger to see where it is dying...  It is impossible
>>to debug something I can't produce...
>
>Ok. I get for UNIX (AIX3.2.5)
>
>dbx ./crafty core
>dbx Version 3.1
>Type 'help' for help.
>reading symbolic information ...
>[using memory image in core]
>
>segmentation violation in EPDTBScore at line 7278 in file "epd.c"
> 7278                                   if (rb.rbv[sq] == cp)
>(dbx)
>


aha... something in Steven Edward's EPD code there...  although I
have no clue why it should even be called since there are more than
5 pieces on the board...  have you modified the source in any way,
with respect to search.c calling EGTBScore()?

I'll look at his code to see if I see anything fishy, although it
doesn't explain why it doesn't fail for me...



>>sorry, but your idea is *wrong*.  Given the choice of being right 99.999%
>>of the time, or .001% of the time, the choice is obvious.  I do *not* want
>>to trade into a KB vs KB, simply so that I can find the mate in 1 in the 4
>>positions where it is possible in such a position.  Crafty is written to play
>>chess, not solve problems...
>
>I don't make that difference. Problems are especially beautyfull. but I
>accept your point.
>
>
>IMHO deep blue can solve a lot of studies. Simply by searching. But also
>the rare cases have to be searched.
>There was (is) great interest in Ferret. I hope that Ferret can do without
>the "insufficient material feature" and I hope that if it uses null move
>it has a zugzwang detection. That would do for me.
>
>Kind regards
>Bernhard



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