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Subject: Re: not using nullmove?

Author: Dann Corbit

Date: 23:09:38 02/13/04

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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.
>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).

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