Author: Thorsten Czub
Date: 13:26:37 07/30/02
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On July 30, 2002 at 15:17:39, Uri Blass 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 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 > >I thought about the opposite. > >Null move pruning was considered to be a dangerous pruning because you may miss >threats and this is probably the reason that programmers like richard lang never >used it. > >If you want to be more careful in pruning you may try to prune only moves when >the score after null move is at least beta+margin. > >Thorsten asked about an old program so it is logical to guess that they tried to >reduce the demage by using null move margin. > >It is possible to find who is right simply by finding if increasing the null >move margin help the program to get bigger depth. > >If increasing the null move margin help the program to get bigger nominal depth >then Tony is probably right. > >Uri thanks. i will let you know :-))) about it. i will try it out.
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