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

Author: Omid David

Date: 14:04:05 07/11/02

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On July 11, 2002 at 16:55:19, Frank Phillips wrote:

>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?
>Can you report anything about the constraints placed on R=3/2 (depth to
>frontier, number of pieces left etc) and whether your research indicates the
>effect of varying the constraints.

Self-play matches where conducted using random opening book selection (no given
starting position). In test suites, all positions which one or both sides had
only king and pawns where discarded.

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