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Subject: Re: Evaluation-based Reductions and/or Extensions

Author: Tom Likens

Date: 18:07:34 12/28/03

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On December 28, 2003 at 16:55:49, Tord Romstad wrote:

>Hi Tom!
>
>That's precisely what I am doing in Gothmog, as you probably know.  I'm glad
>to hear that you try similar ideas, and that your first results are promising.
>I've found that it takes lots of tuning and testing before it works well,
>but I think such techniques have great potential in the long run.  If it's
>done right, most of the improvements you do in your evaluation function will
>automatically improve the accuracy of your search.

When I first started experimenting with this idea I was *very* aggressive.
Interesting it didn't really hurt the programs tactics and it seemed to
reach much deeper depths while searching, so I was very excited.
Unfortunately, when I played the new version against the older non-pruning
version it lost rather badly.  So, now I'm starting out in a more
conservative fashion and tuning the reductions based on actual games.

>>My (obvious) question, how do other programmers deal with this phenomenon?
>>I suppose ignoring it is one option, but I'm hoping there is a better
>>solution.
>
>I agree that this problem is extremely annoying, and I have spent lots of
>time and effort trying to find a solution.  Unfortunately, I still haven't
>found any good ideas. I asked a question about exactly this problem here in
>CCC just a couple of days ago, but the only person who replied was Dieter
>Bürssner, who also hadn't found a better solution than just ignoring the
>problem and hoping it wasn't too important.
>
>Tord

The fact that neither yourself nor Dieter have found a satisfactory solution
illustrates the difficulty of the problem.  It may be possible to tag these
nodes when they are saved into the hash table and simply use them for move
ordering, as Uri suggested.  I need to gather some data before I can make
any kind of intelligent decision.  I do agree though that the concept has
*massive* potential.  I wouldn't be surprised if this wasn't part of the
"secret" of the commercial programs, (especially that Tiger fella) ;-)

--tom



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