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Subject: Re: Questions about "Position Learning"

Author: Robert Hyatt

Date: 18:02:03 10/23/99

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On October 23, 1999 at 19:03:55, James T. Walker wrote:

>Hiarcs has a learn file which is limited to 64K in size.  Rebel has an 8k file
>which appears to be for position learning.  Crafty seems unlimited in this area.
>Q. What is the limiting factor on the size of a "Position learning" file?
>

Crafty is actually limited to 64K entries.  I do this because these are
sucked into the hash table and marked as 'permanent'.  I don't want a bunch
of those things totally clogging the hash table...


>All the Chessbase engines use a "Retro-Analysis" to analyze the games/files
>starting at the end and working to the beginning.  This seems like an excellent
>way to find mistakes.

retro-analysis is good and bad.  It can be bad, because while the entries
stay in the hash, as you back up move by move, you get better and better
analysis as you work back. But eventually those older positions get over-
written, and suddenly the eval makes a big change, and this big change has
nothing to do with the game, rather it is a hashing issue.  I tried this when
I first did annotate(), but decided that the fluctuations that occur when the
hash table gets overwritten were more confusing than the deeper analysis was
useful...





>Q.  Why can't this be used for the "Position learning" files?
>
>Humans can examine games and find "mistakes" made by programs.
>Q. Why can't humans contribute to the position learning files in the manner?
>

I am going to do this...  someone asked for such a feature for the kasparov
vs world game...  they want to get into analysis mode, but be able to say
"this position is +9 no matter what you think" and have that as a permanent
(for the duration of the analysis session) hash entry...

That is doable, in the same context as current position learning.





>Just curious.
>Jim Walker



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