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Subject: Re: Fractionial R for Null Move?

Author: Mathieu Pagé

Date: 15:35:29 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  :)

It wont work.

You have 100 nodes as an example and th optimal R=2.2.

If you use R=2
  you get 100 nodes with a value of R near the optimal value.

If you use R=3
  You get 100 nodes with a value of R far of the optimal value (I mean it could
have been nearer).

if you use 20xR=3 and 80xR=2
  You get 80 nodes with value of R near the optimal value and 20 wich could have
been nearer.

I think the firs option is the best. Unless you can say in wich nodes R=3 is
better than R=2. This is already know as Adaptive Null Move I think.

Mathieu P.



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