Author: Ulrich Tuerke
Date: 06:04:57 07/31/02
Go up one level in this thread
On July 31, 2002 at 08:52:41, Uri Blass wrote: >On July 31, 2002 at 07:55:51, Ulrich Tuerke wrote: > >>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 am surprised to hear it because I thought based >on posts that at the time that null move >was invented programmers were afraid >from errors and did not dare to think about R=3. > >I thought that in this situation >the inventors are going to be afraid of >increasing the risk of null move pruning >by other means. You are right. It took some time until the idea was generally accepted and implemented into many programs. But Goetsch and Campbell themselves had suggested already in their original paper several extensions of the algo. One of them was to use R > 1 and another one was the margine which we are talking about here. I'm not sure if they had already suggested recursive use of the null-move, but I think so. Uli > >Uri > > >> >>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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