Author: Ed Schröder
Date: 23:00:57 04/29/04
Go up one level in this thread
On April 29, 2004 at 23:25:59, Robert Hyatt wrote: >On April 29, 2004 at 16:17:34, Ed Schröder wrote: > >>On April 29, 2004 at 14:44:47, Robert Hyatt 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. >> >> >>>Chrilly wasn't the one that started the null-move search stuff. Don Beal was >>>the first I recall reading although Murray Campbell also wrote a paper on the >>>idea. I will try to flip through the surviving Cray Blitz source listing to see >>>exactly when null-move was added to it. All I remember is Burton Wendroff >>>(Lachex) sending me a copy of Murray's paper and saying "try this". (this >>>happened while I was preparing for an ACM or WCCC event). Of course I am >>>talking about R=1, non-recursive, as it was defined "in the good old days".. :) >> >>Actually Don Beal told Frans about nullmove in Cologne 1986, Don at that time >>only used nullmove in QS. Don did not use nullmove as we know it today, that >>came after Chrilly's article. >> >>Ed >Yes, but Campbell defined "the null-move observation" exactly as it is used >today (no move played, reduce depth, if it fails high, then let the search fail >high with no more searching.) He even suggested that R=2 needs serious testing. Did Campbell mention recursive nullmove too? Because that's where the real strength of the algorithm comes from. >Chrilly's main advancement was using the null-move observation to detect threats >and extend the search when the condition was met. I don't know of anyone that >really does this today. I did it back around version 9, but stopped due to the >high cost and low return... As far as I can remember the article was about detecting mate-threats only, I could be wrong. I use it, when the first nullmove returns a mate-value I extend one ply. My best, Ed
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