Author: Sune Fischer
Date: 15:40:05 03/17/04
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On March 17, 2004 at 18:16:11, Mridul Muralidharan wrote: >>> Take a set of quiet positions and it will be possible to see history being >>>totally equal or slightly worse or slightly better than random (or no) move >>>ordering. >> >>I don't think so, random is about as bad as you can get. >> >>History tables, while they may not be perfect, are certainly an improvement upon >>randomness. > >Maybe I forgot to add YMMV :) > >But my expiriments on crafty have lead me to believe that crafty can do better >than history. Well, that goes without saying because one can _always_ do better! :) >Ofcourse , for me , history totally sucks - no doubt about it. > >History is damn cheap (well almost :) ) , and almost all sites on chess >programming have it mentioned ;) so anyone starting off would think it is like a >gospel truths that history performs well. > >The amount of attention that it gets and the amount of chess programs that it >has made its way into is dispropotionate to the benifit it gives :) They are easy to explain and easy to implement, perhaps that's a factor. >If people expiriment more (and more often too !) , then you may come up with >other schemes that are far better. Of course. HH is only the last resort but every bit needs tweaking :) >I dont use history or pcsq or any crude piece/from-to based move ordering >schemes anymore - gave them up about 6 months or so after starting seriously. >I still keep revisiting them , tweaking them , etc due the obvious "cheapness" >in these schemes - IF i can get a good solution - then why not use it ! ;) >But of all the initial attempts , I found history totally bad and nothing has >changed my opinion about this till date. I agree there are far better ways, most of them more expensive too. I don't see any reason to call them "totally bad" though (not unless you intend to mock those that use them ;) as they clearly are better than doing nothing. YMWV. (your milage _will_ vary) >(Even the very interesting study by someone a few months (?) back on various >move ordering heuretics was not really convincing since I did the same and found >contrary results .... maybe mine of his code had bugs ;) ) > >Maybe in initial years of computer chess when processing power was very very >pricy then history might have had some kind of benifit (whenever with luck it >does not deteriorate into randomness ...) but harping about same ideas 10 - 25 >years later still does not smack well of progressive and scientific thinking >.... >Today , you can definitely attempt better schemes - a 50 knps drop if it leads >to 20 % smaller tree is an amazing gain today - while such a propotionate speed >drop when programs were barely doing 6 - 8 ply was unthinkable earlier on ! >(reasons for this should be obvious ...) > >Ok , enough rambling , 3:30 at night can do crazy things to brain :( Your clock must be broken, mine is showing 00:34 am. :) >Good night , Best Regards and have a "happy history" ;) Alright, nighty night then. -S. >Mridul
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