Author: Sune Fischer
Date: 00:55:45 01/11/02
Go up one level in this thread
On January 10, 2002 at 21:39:07, Vincent Diepeveen wrote: Hmm I'm not sure I believe you, what good is it to have a strong positional knowledge if you get killed in tactics? Someone once said, that good positional knowledge was worth another ply tactically, at best. Though that may be stretching it a bit, I think a 15 ply searcher will get killed by a 20 ply searcher too often. At the end of the day, chess is nothing but tactics, just very deep tactics of cause. -S. >On January 10, 2002 at 17:50:46, Dan Andersson wrote: > >>One reason that search is discussed so much is, IMO. That the static scores of >>evaluators are 'always' wrong. It means that an efficient and intelligent search >>(including extensions) will trumph a less efficient search allmost all the time. >>Due to the fact that the search essentially 'mines' the search space for a more >>accurate evaluation. A much better approach is to tailor your evaluator to your >>search. Granted that a good evaluator is preferable to a bad one. But making it >>behave consistently inside your search framework is the number one priority. > >Not exactly the truth. A simple alfabetasearch + nullmove + hashtables >+ simple qsearch is going to beat any other program if evaluation is >real good and the opponents is no good. > >Whatever your search, remember that the pro's are 99% busy with just >evaluation and testing. > >Search is like 0.001% of the time invested. > >the reason why most like to fiddle with search is > - lossless speedups are easy to measure > - it is easy to modify something and test > - there are great tactical testsets to see whether your > search is finding tactical more (also at the same time saying > that for tournament results this says nothing about engine > strength) > >the reason why most do not discuss evaluation much > - the pro's keep it a secret that they win because of evaluation, > they say nothing anyway. But let's give example to Tiger. What is > the BIG difference between tiger 0.x versus the current tiger2? > Right, it is evaluation. What did Christophe post here not too long > ago? Right: "only searching deeper works". In the meantime only thing > improved in tiger is evaluation. Of course congrats Christophe that you > keep managing to improve it! > > Try endgame on fritz3 versus fritz7a. Fritz7a is with induction everywhere > better. It even slowe down. > > At nowadays hardware fritz3 would search like 20 ply easily, also in > middlegame (provided you improve its hashtables a bit by rewriting hashtable > to a better approach. > > Reason is the what i call Peter Gillgasch lemma (he gave this > to me as reason why version of Darkthought he programmed in > alpha-assembly at the time searched so deep): if eval sucks then > *nearly everything* gives a cutoff, especially if you are material > ahead. > > I remember that on 4x400Mhz linux machine in worldchamps paderborn 1999 > i searched in *any* endgame like 20 ply easily. This with like 350MB > hash and a machine in total less than 1.6Ghz. > > Right now i have 2 x 1.2Ghz at home but i sure do not get even *close* > to 20 ply in the same endgames. > > DIEP 1999 , its endgame was major crap. Only after world champs 2000 > i started improving DIEP's endgame. Right now it definitely is way > stronger there than it used to be. > > - But the biggest 2 reasons why evaluation hardly gets discussed is > because it is hard work and the average guy posting here has a rating > way less than half mine. > >Best regards, >Vincent > >>But >>discussions of evaluation factors are always good. As for good/bad bishops a >>dynamically computed piece square table is an option. And not all that expensive >>if you hash it, or make an 'el cheapo' function. The bishop might not be bad if >>it occupies an active square. Or it might be very bad in an open position if it >>is acting as a blockading piece for a pawn. >> >>MvH Dan Andersson
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