Author: scott farrell
Date: 14:52:45 02/14/04
Go up one level in this thread
On February 14, 2004 at 05:28:04, Uri Blass wrote: >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 I read a post recently that Ed uses, but not like we do. He uses it to confirm a reduction or pruning. He uses it around alpha and not beta, and doesnt use it to cut off. Scott
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