Author: blass uri
Date: 23:19:15 08/03/99
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On August 03, 1999 at 23:08:55, Dann Corbit wrote: >On August 03, 1999 at 23:00:44, Ricardo Gibert wrote: >>On August 03, 1999 at 22:35:16, Dann Corbit wrote: >>>Has anyone tried something like this for pawn value: >>>ranks advanced = 0, value = 1.000 = 100 centipawn >>>ranks advanced = 1, value = 1.000 >>>ranks advanced = 2, value = 1.013 >>>ranks advanced = 3, value = 1.065 >>>ranks advanced = 4, value = 1.299 >>>ranks advanced = 5, value = 2.547 >>>ranks advanced = 6, value = 10.347 >>> >>>This is derived from the following formula: >>>pawn_value = 1.0 + (ranks_advanced! - 1.0) * .013; >>> >>>I believe that the value of a pawn is a factorial of the number of squares it >>>has advanced... >>> >>>The reason that I think such a scheme is reasonable is as follows: >>>A pawn gains very little value on the first two moves, except some control of >>>the forward squares. However, a pawn two squares from queening is a problem, >>>and a pawn one square from queening is a *big* problem. You would gladly tie up >>>a knight to prevent queening, I think. Hence, it's value is nearly the value of >>>the knight. And, at the moment of queening, it is worth slightly *more* than a >>>queen. The reason it is worth more than a queen is that it can become a queen, >>>or another piece -- if that is advantageous. A queen cannot do that. So, the >>>moment it lands on the promotion square it has a value of something just over >>>10. >>> >>>Thoughts? >> >>I assume you are talking about passed pawns. I would think that this would make >>your evals wildly inaccurate, counterfeiting the values of alpha & beta. Some >>pawns are on the 7th spell death while others are just material to be picked up >>by your opponent. Better to do an extension. The numbers you give, better >>represent the "attention" the pawn should be paid. >It could not upset the eval by more that 150 centipawns, since the final advance >gives you a queen (if you want). I think that the pawns may just be 'material >to be picked up' because we are not giving them the proper attention. If we >considered them to have the value listed above, they would be more carefully >guarded as they race for the back. I think that also, it would prove an >attractor to pull pawns towards promotion. Programs try to promote much too >late. On the other hand, the values stated do not accurately reflect the >destructive power of the pawn, since a pawn one square from promotion is still >just a pawn. > >What I was wondering is if anyone had actually *tried* it to see what would >happen. It seems like it might be an easy enough experiment for many programs. I do not think that increasing the evaluation of passed pawns is a good idea. I saw cases when programs overevaluated passed pawns. I remember a game between craty and Junior in mclane's tournament when both programs evaluated Junior's position as more than 1 pawn advantage because Junior had a passed pawn in the 7th rank and crafty took the weak passed pawn and did a draw. I think that a pawn in the 8th rank is not equal more then a queen. cases when an underpromotion help are rare when the fact it is the opponent's move after the promotion give the opponent more important advantage. Uri
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