Author: Robert Hyatt
Date: 07:58:12 12/16/05
Go up one level in this thread
On December 16, 2005 at 01:28:19, Chrilly Donninger wrote: >On December 15, 2005 at 21:55:02, Robert Hyatt wrote: > >>On December 15, 2005 at 21:14:45, Sergei S. Markoff wrote: >> >>>>>>I find that VERY hard to believe. That concept has been around a >>>>>>very long-time. >>>>> >>>>>Really? Where it was introduced by the first time? >>>> >>>>Don't know about the first time, but GNUChess (v4) uses the same approach, >>>>albeit only for some king eval terms, and many programs scale things by >>>>material, although not necessarily as nicely as Fruit does. >>> >>>Well, I think such material dependence for some factors was in Kaissa too :) But >>>I never seen before Fruit the united concept of opening/endgame evaluation. Also >>>material dependence of some factors seems to be appeared at first time in Fruit. >>>For example -- piece mobility depends of stage. >> >> >>That's not new at all. I can think of several programs that have done this >>"scaled" eval approach since the late 1970's... If you look at Crafty's eval, >>you will see it done much more subtly than what is done in Fruit. Individual >>eval terms are scaled by material when appropriate. Endgame things like passed >>pawns, distant passed pawns, pawn majorities/candidate passers, all scale up as >>material comes off. King safety scales down in the same way. > > >I scale the terms also individually. I think most programms do that. But the >Fruit approach has some beauty. With the individual approach one has more >freedom for tuning. The relation between material and the eval terms differ. But >one can also introduce inconsistencies in the eval. Its hard to keep everything >balanced. The formula is typically for Fruits KISS approach. Its hard to do any >stupid things with the Fruit-formula. > >Chrilly > >Chrilly Would not disagree. Am in the middle of a complete re-vamp of the crafty eval code, and I am going back to "simple is better". There was simply way too much complexity in the old way with "3rd order terms" (where groups of pieces contribute to a term (2nd order) and then these 2nd order terms interact to produce a 3rd order result.) Nearly impossible to understand at times... I've come up with a better way to scale eval terms for each piece so that I can control the total positional score a piece can contribute, without having to tune each individual weight to adjust this. Hopefully, simple turns out to be better in addition to easier...
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