Author: José Carlos
Date: 06:15:35 04/11/01
Go up one level in this thread
On April 10, 2001 at 13:57:33, Tony Werten wrote: >On April 10, 2001 at 09:16:28, José Carlos wrote: > >>On April 10, 2001 at 06:58:26, Tony Werten wrote: >> >>>On April 09, 2001 at 22:25:14, Robert Hyatt wrote: >>> >>>>On April 09, 2001 at 21:17:59, Normand M. Blais wrote: >>>> >>>>>On April 09, 2001 at 18:20:07, Robert Hyatt wrote: >>>>> >>>>>>On April 09, 2001 at 16:49:21, Normand M. Blais wrote: >>>>>> >>>>>>>On April 09, 2001 at 16:21:56, Andrei Fortuna wrote: >>>>>>> >>>>>>> >>>>>>>>positional score > 2 PAWN_VALUE. And that will hurt my quiescence and my >>>>>>>>futility pruning if I assume that 2*PAWN_VALUE is max positional score. It all >>>>>>>>boils down to the magnitude of the positional scores versus pawn value, I think >>>>>>>>I have to choose either to keep big bonuses and turn futility off (or set a >>>>>>>>bigger margin for futility but in that case it would make futility more >>>>>>>>inefficient) or keep small bonuses and enjoy the reductions I get from futility >>>>>>>>and quiescence. >>>>>>> >>>>>>>What if you multiply the value of the material by 10 (i.e. pawn = 1000 Knight = >>>>>>>3000 Bishop = 3000 Rook = 5000 Queen = 10000 ) and keep the positional score as >>>>>>>it is. >>>>>>> >>>>>>>N.M.B. >>>>>> >>>>>> >>>>>>Then you become _very_ materialistic. You will grab pawns whenever >>>>>>possible, even if it wrecks your king position. You will grab a pawn but >>>>>>leave your opponent with an outside passer that wins. Etc... >>>>> >>>>>I understand that the positional score is related to the material score (the >>>>>pawn or tempi being the unit of measurement). I made a mistake by suggesting >>>>>that the material value can be magnified without adjusting both the positional >>>>>bonuses and penalties. But would it be a good idea to have one more digit to >>>>>work with? A value of 1000, for instance, could represent 100.0. And scores >>>>>like 112.4 and 112.8 could be set apart? Not a sophisticated idea but anyhow. >>>>> >>>>>Regards, >>>>> >>>>>N.M.B. >>>> >>>>I don't personally think the idea of "millipawns" makes a lot of sense. That >>>>is _very_ fine resolution. I used it in Cray Blitz, and in early versions of >>>>Crafty, but it adds to the hash entry size for one thing... >>> >>>XiniX is using it. Not because it makes any sence but I like the idea that I can >>>give small bonusses for some stupid positional thing that I like, without >>>messing up the eval and still having the idea that if two positions score almost >>>the same, it will prefer the one I like. >>> >>>Gives me a sort of personal tough feeling. ( As I said, it's not because it >>>makes any sence ) >>> >>>cheers, >>> >>>Tony >> >> Too fine resolution makes more difficult beta cutoffs, IMO, so, even not >>having tried it myself, I'd say your tree must be bigger that way than it would >>be with smaller resolution. >> I even recall that, some time ago, I think it was John Dart that made a test >>reducing the resolution of his eval to 1/4 pawn, but I actually can't remember >>how did it work. > >You could even return -1,1,0 (lose,win or neither ). You would get a lot of beta >cutoffs, but I don't think it will give you a strong engine. ( maybe a good >matesolver ) Sure. So what you need it something around the middle. A good compromise between eval precision and beta cutoffs. José C. >Tony > >> >> José C.
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