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Subject: Re: Move ordering metric

Author: Peter Kappler

Date: 10:31:21 11/11/03

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On November 11, 2003 at 11:25:59, Robert Hyatt wrote:

>On November 11, 2003 at 11:09:40, José Carlos wrote:
>
>>On November 11, 2003 at 10:52:20, Robert Hyatt wrote:
>>
>>>On November 11, 2003 at 10:42:10, José Carlos wrote:
>>>
>>>>  So far, when I cutoff due to null move, I do BetaCutoffs++ but not
>>>>BetaCutoffsAtFirst++ so my 100 * BCAF / BC statistic gets lowered. Is there an
>>>>standard for this for I can compare with other people numbers? Should I count a
>>>>null move cutoff as a beta cutoff at first? Should I not do BetaCutoffs++?
>>>>
>>>>  José C.
>>>
>>>Don't do anything in that case.  You only care about the ratio of
>>>[cutoffs on first move] : [cutoffs on any but first move].
>>>
>>>The higher that ratio the better.
>>
>>  So you mean not to count null move cutoffs as cutoffs at all, right?
>>
>>  José C.
>
>
>Right.  or you might count null-move searches done, and null-move searches
>that failed high, if you want to know how effective null-move search is.  But
>it is clearly independent of the idea of base move ordering where the first move
>should cause a cutoff if one is going to happen.

This first-move-beta-cutoff metric is something that has always bothered me.  In
previous discussions, people have reported an average of ~90%.  For my program,
it's more like 80%, and I'd like to understand why.  I don't use a SEE to
eliminate bad captures, and also don't use internal iterative deepening.
Perhaps that's enough to explain the difference?

If either of you have time to run a quick test with one or both of these
features disabled in your program, I'd be interested to hear how it affects the
FMBC %.

-Peter



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