Computer Chess Club Archives




Subject: Re: Null-Move: Difference between R = 2 and R = 3 in action

Author: Robert Hyatt

Date: 14:35:55 07/11/02

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On July 11, 2002 at 16:38:50, Omid David wrote:

>As part of an extensive research (will be published soon), we tested null-move
>pruning with fixed depth reductions of R=2 and R=3 on about 800 positions of
>"mate in 4" (searched to depth of 8 plies) and "mate in 5" (searched to depth of
>10 plies). The results naturally show that R=2 has greater tactical performance
>(greater number of checkmate detection). However, we also conducted about
>hundred self-play matches under 60min/game time control between R=2 and R=3. The
>outcome is a rather balanced result (R=2 only a little better). Considering that
>the tests where conducted on a rather slow engine (100k nps), on faster engines
>R=3 is expected to perform better.
>So, apparently R=2 is not _by_far_ better than R=3 as some assume. I believe
>Bruce Moreland had also some good results with R=3 that show it's not too
>inferior to R=2. Has anyone conducted similar experiments?

I tried R=3, but didn't like it overall a couple of years back.  I then
started with the R=2/3 approach I am using today and it has been pretty solid
IMHO.  But again, R=3 and even R=3/4 is due for some detailed testing I think.

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