Author: Anthony Cozzie
Date: 07:22:31 12/31/03
Go up one level in this thread
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
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