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Subject: Re: Endgame trap; some progs see it - How is it found? e.g. Crafty?

Author: Robert Hyatt

Date: 17:38:48 05/27/99

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On May 27, 1999 at 19:04:24, Paul Richards wrote:

>On May 26, 1999 at 23:24:02, Robert Hyatt wrote:
>
>>OK.. I read the whole thread, and tried it.  It is the piece of knowledge
>>that says K + B + RP on wrong color draws if the opposing king can get to the
>>queening square before the pawn.  That is why Crafty plays Nh6 as black and
>>_never_ considers gxh6.  If you play Nh6, a 1 ply search rejects gh because it
>>evaluates to DRAW.  Very simple answer after looking at it..   so forget my
>>first answer.  That happens, but not in this case...
>
>What's interesting is that a 1-ply search rejects gxh6 immediately, but
>if you set Crafty to analyze for black after gxh6, it searches to 15-16 ply
>before seeing that Kh8 leads to the draw.  As a matter of fact it awarded
>Kh8 a !! all by itself, which I thought was a very nice touch. :)  So it
>appears that it decides on the draw different ways before and after gxh6,
>or that the special knowledge code is invoked at a different point?

1.  make sure you don't have a "position.bin" file.  That kind of learning
data can screw things up if you played with this position a bit.

2.  if not, all I get for any K move, from ply 1 on is 0.00...  ie Kxh6 is a
draw and it doesn't vary.

Bet you got 'learned' into this.  :)  Happens to me frequently when debugging,
so much so that my test Makefile does a "rm position.*" every time I compile.




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