Computer Chess Club Archives




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

Author: Robert Hyatt

Date: 07:59:55 04/30/04

Go up one level in this thread

On April 30, 2004 at 08:02:57, Uri Blass wrote:

>On April 30, 2004 at 07:49:10, Vincent Diepeveen 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.
>>That's what i mean, using a simple form of search in those days meant fullwidth.
>>>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.
>>Frans' world title in 1995 had a huge positive impact.
>>>>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.
>>I see that different, but i must add the note that Rebel is basically tactical
>>selective in main search already and DIEP isn't. I do very little extensions in
>>diep other than singular. Even check hardly gets extended, i'll extend it when
>>it's singular.
>>>>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.
>>Well of course when programming for a 10Mhz machine i would add huge selectivity
>>too, but i'm just talking about a theoretical math here now.
>>My code size doesn't even fit within the ROMs you had in 1991 :)
>>>>My point is would you have become world champion in 1991 searching 3 ply?
>>>8-10 plies was sufficient.
>>8-10 plies at 10Mhz with for its time a great eval is really a grandmaster piece
>>of work. I actually was not so long ago at a friend of mine (IM) having a
>>chessmachine with inside an Ed Schroeder program. I really was amazed that you
>>got such a depth out of such a tiny hardware!
>>In fact it completely outsearches diep 1997 which got 8 ply at the world champs
>>1997 at a PII300Mhz.
>>>>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.
>>No kidding.
>>Huber clearly has proven that with MTD and a simple eval (basically material)
>>you can search depths of 30+ ply.
>>The passive way in which fritz3 developed its pieces is very helpful. You get
>>*everywhere* nullmove cutoffs.
>>With an agressive tuned engine such a thing is of course a lot more difficult to
>>do, if not nearly impossible at todays hardware.
>>>>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.
>>In 1999 fritz searched 17 ply everywhere at a quad xeon 500Mhz in middlegame.
>>In 2003 fritz at a quad xeon 2.8Ghz searched 14 ply in middlegame.
>>Those 14 ply from fritz2003 however completely destroy that 17 ply from
>>I know why this happens. I see it at many engines including DIEP.
>I can only say that number of plies is meaningless.
>It even does not mean that it is better in tactics.
>I can search more than 100 plies forward if I do enough reductions and every
>move is reduced by at least 10 plies.
>I do not understand why do people discuss about it.

It gives them something to talk about when all their other arguments are based
on fallacy...

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