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Subject: Re: Two tactical positions

Author: Jon Dart

Date: 21:02:37 11/23/99

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On November 23, 1999 at 20:10:21, James Robertson wrote:

>On November 23, 1999 at 20:02:09, Jon Dart wrote:
>
>>In position #1, Crafty 16.16 switches from Qxh4 to Qh6 at 4 ply
>>in under 1 second. So does my program Arasan. The eval is around
>>-1.8, but Qxh4 is evaluated much worse.
>>
>>--Jon
>
>My program does the same, but later it chooses Qxh4 again because the threat it
>saw before was not real. It again switches back to Qh6 at ply 12, though. Do
>Arasan or Crafty do the same?
>

No, neither seems to behave this way. I let Arasan go 12 ply and got this:

ply 1.  Qxh4    1 seconds.      score:  -0.77   2 nodes.
ply 1.  Qxh4    1 seconds.      score:   0.30   39 nodes.
ply 2.  Qxh4    1 seconds.      score:   0.30   265 nodes.
ply 2.  Qxh4    1 seconds.      score:  -0.33   306 nodes.
ply 2.  Qxh4    1 seconds.      score:  -0.33   344 nodes.
ply 3.  Qxh4    1 seconds.      score:  -0.42   2014 nodes.
ply 4.  Qxh4    1 seconds.      score:  -0.42   6541 nodes.
ply 4.  Qh6     1 seconds.      score:  -1.70   9663 nodes.
ply 4.  Qh6     1 seconds.      score:  -1.70   10435 nodes.
ply 5.  Qh6     1 seconds.      score:  -1.50   17549 nodes.
ply 6.  Qh6     1 seconds.      score:  -1.58   45751 nodes.
ply 7.  Qh6     2 seconds.      score:  -1.55   129520 nodes.
ply 8.  Qh6     6 seconds.      score:  -1.67   458897 nodes.
ply 9.  Qh6     15 seconds.     score:  -1.64   1195065 nodes.
ply 10. Qh6     33 seconds.     score:  -1.77   2757884 nodes.
ply 11. Qh6     77 seconds.     score:  -1.77   6875898 nodes.
ply 12. Qh6     299 seconds.    score:  -1.67   26418042 nodes.

Maybe you've got over-aggressive forward pruning or lazy eval?
(It could be a lot of other things, but these come to mind).

--Jon



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