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

Author: Uri Blass

Date: 14:41:08 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).

This is not the right test.
It is clear that if you search to fix depth R=2 is going to be better.

The question is what happens when you search for the same time.


 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.

I think that a better test should include different programs and not the same
program against itself.

Another point is that R=2 and R=3 are not the only possibilities.
>
>So, apparently R=2 is not _by_far_ better than R=3 as some assume.

I suspect that it is dependent on the program(results may be different for
programs with different qsearch and different evaluation).

Uri



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