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Subject: Re: Question on RootSearch

Author: William Bryant

Date: 10:37:31 09/08/99

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On September 08, 1999 at 11:20:54, James Robertson wrote:
>
>I have had a terrible time trying to implement something like this, and finally
>gave up. How much does it help Crafty/Screamer? Is it worth it to try to get it
>to work?
>
>James

I also had a terrible time until I finally worked out the errors, and there were
several.  The problem lies in how to structure the aspiration windows,
the researches for fail-high and fail-low, and then adding PVS searching on top
of it.

Bob and others were a lot of help.

My problem now is that my SEE seems to be pruning to much.  On rather quiet
lines, it does a great job of getting to the next ply.  On positional issues,
it makes the program play much poorer.

For Example, on LCT-II the POS part of the suite, the score drops in half,
missing several of the answers with the Delta-SEE pruning in place.  It makes up
some of this in the tactical middle game portion.

When playing the two versions against each other, at short time controls
(2s/move), the SEE version clearly dominates.  At longer controls (5-10s/move or
greater), the slower more positional version does better.

I am operating under the assumption that there is a bug somewhere and that
eventually the SEE will give me the speed without sacrificing the positional
skill.

It is possible that the positional 'insight' is accidental, finding the right
move without knowing why.

Any insights in getting you SEE to work would be appreciated.

William
wbryant@ix.netcom.com





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