Computer Chess Club Archives




Subject: Re: When to do a null move search - an experiment

Author: Ed Schröder

Date: 23:17:02 04/29/04

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On April 29, 2004 at 23:22:26, Robert Hyatt wrote:

>On April 29, 2004 at 19:26:32, Ed Schröder wrote:
>>On April 29, 2004 at 18:05:29, Omid David Tabibi wrote:
>>>On April 29, 2004 at 09:28:53, Ed Schröder wrote:
>>>>On April 29, 2004 at 07:37:23, Vincent Diepeveen wrote:
>>>>[ snips ]
>>>>>>This is all very poor Vince, I assume you don't play much with nowadays top
>>>>>>programs. From 1982 to 2001 Rebel won its games by positional understanding and
>>>>>>not by search and Rebel lost its games because it was outsearched. Today Rebel
>>>>>>isn't outsearched at all, it now loses its games because the current top
>>>>>>programs have a better positional understanding than Rebel.
>>>>>>You should have a good look at the current tops, the positional progress has
>>>>>>been great the last years. To me it all seems to indicate (provided your search
>>>>>>is okay) the only way to make progress is to improve on chess knowledge. But
>>>>>>what's new, I already came to that conclusion in 1986 after some intensive talks
>>>>>>with Hans Berliner.
>>>>>What i mean is Ed, is that you would not have accomplished the great results
>>>>>with Rebel which you managed, had you just searched with a fullwidth search +
>>>>>bunch of checks in qsearch.
>>>>No of course not, brute force is silly, Rebel since day 1 has been a selective
>>>>program. But I am getting your point, in the days before the nullmove was
>>>>discovered Genius and Rebel had the best (static) selective search, a dominant
>>>>factor in their successes, is that what you meant to say? If so, it is true.
>>>>If only Frans had kept his mouth shut to Chrilly (Chrilly leaking nullmove in
>>>>the ICCA journal) it is very likely Fritz would been the next Richard Lang still
>>>>dominating all the rating lists and WCC's for the last decade. But Frans didn't
>>>>and then all bets were off.
>>>Donninger published the article in 1993. Before that, there were two other
>>>publications dealing with null-move:
>>Yes, nullmove as we use it today, the other 2 articles not.

>Campbell's paper is _exactly_ as I do it today less the recursive nature.  He
>specifically mentioned different R values and said more testing with R=2 was

But missing the recursive ingredient. Nullmove without recursion is a nice
reduction idea, nullmove with recursion changes a brute force program into a
powerful selective search program.

Beal and Campbell (in that order) deserve credit for the original nullmove idea,
Frans Morsch for adding the recursion element.


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