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Subject: Re: Fractionial R for Null Move?

Author: Robert Hyatt

Date: 17:02:45 08/15/04

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On August 15, 2004 at 17:33:39, Bruce Cleaver wrote:

>Here's an idea: most programs implement nullmove with R = 2 or R=3 (even
>adaptive nullmove uses R=1, 2, or 3).
>
>Suppose the truly optimal value for R is at 2.2 (not 2.0), the idea being that
>you always reduce the search 2 plies, and then 20% of the time (done
>probabilistically) reduce 3 plies (i.e. if random() <= 0.2, R = 3 else R = 2).
>The same goes for R = 3, or whatever integer value you are using.
>
>I know it goes against the grain having a non-deterministic approach, but an
>extra
>20% of the search done at R = 3 vice R = 2 could yield large benefits (or,
>terrible blunders, of course).  R = 4 is way too large by experience, but maybe
>R = 3.1 is better than R = 3, and R = 2.5 is better than R = 2
>
>Just an idea  :)


I have tried this in the past.  IE I use a R value of 3 that drops to two near
the leaves, in one unit-step-function type of "drop".  I have tried reducing it
fractionally so that rather than a sudden drop from 3 to 2, there is a gradual
drop from 3 to 2 in fractional decrements.  I didn't find any particular plus or
minus and didn't keep it.  It is still in my notes for "something to play more
with when I have time..."




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