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Subject: Re: Null move and move ordering stats

Author: Peter Kappler

Date: 22:45:37 12/19/01

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On December 19, 2001 at 14:18:21, James Swafford wrote:

>
>I'm just now getting around to implementing a null move search in
>the dinky little thing I've been playing around with lately.
>
>One of the move ordering stats I keep track of is the ratio of
>fail highs on the first mv vs. the number of total fail highs.
>Previously this number has been at 87% for the first 100 problems
>of the Win at Chess suite.  (My eval is so simple I don't bother
>testing more than that yet. :) )
>
>With a pretty kludgy null search with R=2, I'm getting a few more
>problems right, and searching a little deeper on average.  An
>observation I made, though, is that the ratio mentioned above fell
>to 78% - a delta of 9%.
>
>At first glance that makes sense to me, though I'll have to think
>about it a little more later.  It leads me to wonder, though,
>if this is consistent with more sophisticated engines.
>
>For those out there that keep track of that ratio, have you measured
>it without a null search?  I'd be interested in hearing the numbers
>with and without the null search, just to be sure I didn't break
>something.
>

Hi James,

Here are Grok's numbers (full-width search only, not quiescence):

null move, futility pruning:       77%
null move, NO futility pruning:    82%
NO null move, NO futility pruning: 85%

I guess I need to do some work on my move ordering.

-Peter





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