Computer Chess Club Archives




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

Author: Omid David Tabibi

Date: 15:05:29 04/29/04

Go up one level in this thread

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:

Beal, D.F. (1989). Experiments with the null move. Advances in Computer Chess
5, (Ed. D.F. Beal) , pp. 65--79.

Goetsch, G. and Campbell, M.S. (1990). Experiments with the null-move heuristic.
Computers, Chess, and Cognition, (Eds. T.A. Marsland and J. Schaeffer), pp.

>>I am under the impression that you just like diep try checks at several depths
>>in the qsearch. In diep i can try at the entire 32 ply of the qsearch checks.
>Checks in QS are relative cheap nevertheless I have limited them more and more
>the last years. There is little sense doing long range QS checks if you already
>hit 12-14 plies.
>>Doing things like attacks in eval and mobility and scans for all kind of things
>>which are trivial for chessplayers and i do not even dare to write down the name
>>for here, they slow down once engine.
>>I would search 3 ply at 1991 hardware with it, simply because the code size is
>>so huge, the nps at 1991 machine (i had a 10Mhz XT at the time) would be around
>>a 100 nodes a second or so.
>You are overreacting of course.
>>My point is would you have become world champion in 1991 searching 3 ply?
>8-10 plies was sufficient.
>>I very deliberately ask it this way, because fritz3 (1995) searching at todays
>>hardware handsdown would search 20 ply in any middlegame, when it would be
>>converted. Apart from that it single cpu would search 3.5 million nodes a second
>>hands down.
>20 plies?
>Come on.
>>Todays fritz searched in 2003 world champs at a quad xeon 2.8Ghz about 13-15
>>The 2003 fritz at a 386 , 10Mhz would have a problem getting beyond 4 ply.
>I don't believe that.
>>Would you beat it with Rebel-Madrid?
>Fritz3 was a weak program, in tactics and positional play. Fritz5 was a
>revelation, excellent search for those days (the nullmove era starts here) still
>Fritz5 was positional weak. Rebel at that time was typically out-searched by 2-3
>average, it had to win its games by positional play. Then from Fritz6,7 and 8
>Fritz slowly became an excellent positional player.
>And regarding Rebel at 1991, don't get too exited, you can't imagine the number
>of holes in its selective search at that time.
>My best,

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