Author: Tony Werten
Date: 10:57:33 04/10/01
Go up one level in this thread
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 ) Tony > > José C.
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