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Subject: Re: Nullmove: when to avoid it? Why not when depth=1?

Author: Robert Hyatt

Date: 07:34:23 03/03/01

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On March 02, 2001 at 23:07:49, Ernst A. Heinz wrote:

>>>>Why does it make sense? I have not yet tried it but I don't understand why
>>>>should it be better? Do you have any opinions? I allways want to understand the
>>>>features I put into my engine and I don't get this one...
>>>
>>>Easy -- the relative cost of a depth-reduced null-move search
>>>at frontier nodes (with a remaining depth of 1 ply) is just
>>>too high. Most normal searches from there also go straight into
>>>quiescence mode and the gain of null-move cutoffs does not seem
>>>to outweigh the added null-move search effort.
>>>
>>>=Ernst=
>>
>>I tried this for a quick test.  It is actually slower overall than doing
>>null-move everywhere.  A couple of positions were faster.  But more were
>>slower.  I ran all the kopec positions...
>
>As usual, your mileage may vary and it does not work for
>all programs. Do you apply futility pruning at frontier nodes?
>
>If not, this may explain your negative results because you are
>much less selective at frontier nodes then which increases the
>chances of the null-move overhead to pay off.
>
>=Ernst=


I don't do futility pruning at all...  I stopped a year or two ago...



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