Author: Christophe Theron
Date: 11:24:08 02/15/04
Go up one level in this thread
On February 14, 2004 at 17:52:45, scott farrell wrote: >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 What Ed calls alpha is what we beta. Christophe
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