Author: Uri Blass
Date: 02:28:04 02/14/04
Go up one level in this thread
On February 14, 2004 at 02:09:38, Dann Corbit wrote: >On February 13, 2004 at 12:51:08, Uri Blass wrote: > >>On February 13, 2004 at 12:41:41, Tord Romstad wrote: >> >>>On February 13, 2004 at 12:28:26, Mike S. wrote: >>> >>>>On February 13, 2004 at 11:07:02, Tord Romstad wrote: >>>> >>>>>(...) That several of the top commercial >>>>>programs do not use null move (at least not in the conventional way) is >>>>>further evidence that it is possible to come up with something better. >>>> >>>>Are you sure that there are top engines which don't use nullmove? Maybe they >>>>"just" combine it with some zugzwang detection, or switch it off depending on >>>>the amount of material earlier than other engines... >>>> >>>>(I think the last engine not using nullmove which was among the top was Chess >>>>Genius, but that was many years ago.) >>>> >>>>I'm aware that some engines are not affected by the zugzwang/nullmove problem as >>>>much as others are. - I'm only asking from the viewpoint of a user and fan, IOW. >>>>no programmer: Is it ok to say, nowadays all top-10 (if not more) engines have >>>>to have nullmove implemented in some way, because without they wouldn't be >>>>competitive in terms of search speed? >>> >>>I guess all strong programs use what Cristophe once called "the null move >>>observation", which consists of the simple fact that in almost all chess >>>positions, there is at least one move which is better than doing nothing. >>>Hence, in a wide sense of the term, all programs do indeed use nullmove. >>> >>>However, everybody does not use standard recursive null move pruning in >>>the form popluarized by Chrilly Donninger in the ICCA Journal a few years >>>ago. Chess Genius and Junior have already been mentioned. Two other >>>examples are Rebel and Chess Tiger. >>> >>>Tord >> >>Rebel and chess tiger use null move pruning. >>They use other reductions but the same also for you. > >At one time, Rebel did not use null move pruning (IIRC). At one time when I began with movei movei also did not use null move pruning. The point is that Ed found that adding null move pruning was productive. Uri
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