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Subject: Re: null move margin ?!

Author: Ulrich Tuerke

Date: 04:55:51 07/31/02

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On July 30, 2002 at 15:02:25, Tony Werten wrote:

>On July 30, 2002 at 13:56:53, Thorsten Czub wrote:
>
>>in an old program i can set the null move margin on or off.
>>what is the function doing ? any ideas or explanations from the programmers?
>
>I'll give it a guess.
>
>Normally when you do a nullmove and the score returned is > beta you get a
>cutoff. The idea is that if doing nothing already gives bigger than beta, doing
>something would give even more.

You're probably right, Tony. This is an old idea, which had been already
suggested by the nullmove "inventers" Goetsch and Campbell themselves a long
time ago.

I have played around with it several years ago. I came to the conclusion that
it's not worthwhile trying it (microscopically smaller search tree but
nevertheless a certain risk involved to damage the search).

Uli

>
>You can go one step further with this idea. Since doing something would be
>better than doing nothing, then doing nothing doesn't have to be > beta but only
>> beta - margin since I expect that a move is worth at least "margin"
>
>Tony
>
>>
>>what are the effects ?
>>
>>thank you.
>>
>>Thorsten Czub.



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