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Subject: Re: Double Nullmove

Author: Robert Hyatt

Date: 10:27:39 04/25/02

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On April 25, 2002 at 13:15:30, Andreas Herrmann wrote:

>On April 25, 2002 at 12:39:36, J. Wesley Cleveland wrote:
>
>>On April 25, 2002 at 02:54:03, Andreas Herrmann wrote:
>>
>>>Hi,
>>>
>>>I want to implement double nullmove in my chess engine again. Now i'm searching
>>>for Zugzwang postions, which should be solved by double nullmove instead of
>>>normal nullmove.
>>>Another question: How much time costs the double null move in the average.
>>>I have tested it in some positions, and my engine needs about 30 to 40 percent
>>>more time for the same search depth. Is that normal or is that to much.
>>
>
>
>Thanks for your answer.
>
>>That seems like far too much. Are you reducing the search depth again for the
>>second nullmove and only doing it when the first nullmove causes a cutoff?
>
>Yes, i think that's the normal implementation of a double nullmove, and so it's
>inside my source code implemented.
>
>
>>You might also not want to do it too near the leafs, i.e. if the first nullmove goes directly into your quiescence search.
>
>If the first null move goes into the quiescence search, can i do the second
>(normal) null move in each case or never or only if it also doesn't end inside
>the quiescence search?
>
>Andreas

There you just bail out.  null-move in the q-search doesn't make a lot of
sense.



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