Author: Tom Likens
Date: 10:15:50 12/31/03
Go up one level in this thread
On December 31, 2003 at 10:22:31, Anthony Cozzie wrote: >On December 31, 2003 at 09:30:03, Tom Likens wrote: > >>On December 31, 2003 at 07:54:37, Anthony Cozzie wrote: >> >>>On December 31, 2003 at 07:53:49, Anthony Cozzie wrote: >>> >>>>On December 30, 2003 at 22:04:02, Toni wrote: >>>> >>>>>I'm thinking about the values of pieces for a chess program. I have investigated >>>>>some engines and the values they give to pieces vary. Some examples are: >>>>> >>>>>ENGINE knight bishop rook queen >>>>>Faile 1.4.4 3.1 3.25 5 9 >>>>>Amy-0.8.4 3.5 3.5 5.5 11 >>>>>Crafty-19.4, 3 3 5 9 >>>>>Beowulf-2.2 3.2 3.25 5 9.3 (defult personality) >>>>> >>>>>I have to give values for my program and, as I'm not a strong chessplayer I >>>>>would like to know your opinion. Are these differences important? What values >>>>>should be assigned for the highest strength?. The same could be applied to score >>>>>bonuses, but the list is too large. :-) >>>>> >>>>>Thanks >>>>> >>>>>Toni >>>> >>>>Zappa: Knight/Bishop: 3.25 Rook: 5 Queen: 9.75 >>>> >>>>anthony >>> >>> >>>P.S. Do a search for Larry Kaufmann's article. >> >>These are the similar to the values used by Djinn (a pawn is 1). I let the >>position dictate >>wheter the bishop or knight is stronger. The only difference is I give the >>queen a value >>of 9.50. I set up an Excel spreadsheet comparing the values of various piece >>and pawn >>trades and set the values based on what I thought were good/bad trades. For >>example, >>R+4 pawns should be less than the value of a queen, R+P should be less than the >>value >>of two minor pieces, 3 minors > queen etc. It was interesting to see >>Kaufmann's values >>come out so close. >> >>regards, >>--tom > >I really think the queen is almost as strong as the two rooks or 3 minors [very >close]. Kaufmann does suggest 9.5 as an OK value for the queen, though. Crafty >implements some bad trade code where the two minors are given a ~3/4 bonus vs >the rook. Zappa does not, and I've seen it win multiple games when it picks the >rook+outside passer against two minors. > >Another Kaufman idea that Zappa implements is scaling the values of the pieces >wrt # pawns on the board. With 8 pawns on the board, Zappa views a Knight as >3.4 or so and a rook as 4.7 - so it is ready to sac the exchange for a pawn and >some mild positional compensation. OTOH, with 3-4 pawns on the board, Zappa >views a Knight as 3 and a rook as over 5. > >anthony I've considered this but haven't done any experiments yet. It seems to make a lot of sense though. Maybe I'll give this a go in my next round of experiments. Have you tried any self-play matches using static vs. dynamic values in Zappa? --tom
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