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Subject: Re: Fractional Iterative Deepening search

Author: Robert Hyatt

Date: 13:05:01 06/18/00

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On June 18, 2000 at 15:50:43, Gian-Carlo Pascutto wrote:

>
>Hi all
>
>In the discussion of the 'Scalable Search Test' thread with
>Ed Schroeder I mentioned that MTD(n,f) has the nice property
>of making a fail-high pretty constant over time. I.e. the
>search does not blow up as it does in a normal PVS searcher.
>
>Unfortunately it seems that this does not help when moving
>up a ply...it even seems that the results of the MTD'ers
>are quite terrible.
>
>The following though occured to me, if MTD allows you to take
>small steps in the score plane, what about using fractional
>ply increments to take smaller steps in the depth plane?
>
>Many of the best programs have now switched to fractional extensions.
>Thus, fractional search depth must make sense.
>
>Iterative deepening is one of the most important improvements to AB
>search. Thus, it makes sense too.
>
>Still, the programs use whole ply's in their iterative deepening
>search. Why? It would make perfect sense to step in smaller increments
>too. I feel this can even give improvements in tactical situations,
>where the fractional extensions are triggered.
>
>I'm interested if someone has ever done or tested this before. Did it
>work? What were the results?
>
>If you happen to have a program which uses fractional extensions, please
>try it, and let us know how it works out.
>
>--
>GCP


I tried this a good while back, but never really liked what I was getting.  It
is certainly worth trying...  if you use fractional extensions.  If you don't,
it won't do a thing.



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