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Subject: Re: Iterative deepening -- Why add exactly one ply?

Author: Tord Romstad

Date: 10:49:38 05/26/04

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On May 26, 2004 at 13:34:23, Robert Hyatt wrote:

>I have used "IID" for years, but in a very restricted way, namely to handle the
>case along the PV where I have no hash move.  I've never tried it _everywhere_
>before, so have no data.  But I intend to try to see if it is something that
>could work, or if it is a waste...

I am fairly sure you will find that _everywhere_ is a waste.  It is probably
not worth doing near the leaf, you have a hash table move to search, or when
a fail-low is most likely.  Perhaps you should also use a somewhat bigger
reduction factor than in your "along-the PV IID".

Note that it could also be interesting to look for good ways to make use of the
return value of the internal search.  It gives a reasonably reliable estimate
of the value of a full-depth search, and can be useful as an ingredient in
pruning tricks.  The most obvious (and entirely risk-free) case is when the
reduced-depth search returns a mate score.  When this happens, it is clearly
not necessary to do a full-depth search.

Tord



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