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Subject: Re: not using nullmove?

Author: Uri Blass

Date: 02:28:04 02/14/04

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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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