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Subject: Re: Researching after a fail-low

Author: Vincent Diepeveen

Date: 17:07:40 08/17/00

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On August 17, 2000 at 18:05:41, Gian-Carlo Pascutto wrote:

>On August 17, 2000 at 14:43:08, J. Wesley Cleveland wrote:
>
>>When you have a fail-low in a deep search where the value drops significantly,
>>finding an alternate move can take a very long time. This is largely because >the
>>values in the hash table are largely useless, so in effect we are researching
>>the entire tree. It seems to me one should use iterative deepening, and start
>>from ply 1 again.
>
>This technique has been described by Schaeffer a long time ago...
>
>(Obvious question: Why is nearly no-one doing it?)

It works great in my draughts program, and it worked great for DIEP
in the past, but with nowadays huge hashtables and parallellism,
it no longer works for DIEP!

This is one of the things i keep retesting however. I feel that
this feature *might* be used under certain circumstances where it
nearly always will be a big win.

Because logic tells me it should work this research. However if i look
to nodes then i on average need more time a ply (measuring nodes is
not smart in this respect i think).

Perhaps i had a bug in my implementation :)

>--
>GCP



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