Author: Jeremiah Penery
Date: 21:36:29 05/10/99
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On May 10, 1999 at 12:42:43, Gareth McCaughan wrote: >I've observed several instances of the following sort of exchange: > >X: Here's an interesting position. How do programs do on it? >Y: Well, Crafty finds the right move in 25 seconds. >Z: Hah! Fritz only takes 5 seconds. >Jeremiah Penery: My modified Crafty solves it in 0.0000003 seconds. > >I'm intrigued. What have you done to your Crafty? Does it make it a >stronger player generally, or just better at solving certain kinds >of problems? If the former, are your improvements going to make it >into later "official" versions? > >Or does the "modification" consist of running it on a Very Large Cray? :-) Most of what I do is change the evaluation. Piece values are first, usually lower (I like to encourage larger positional scores). I work on king-safety a lot, trying to get it not to succumb to attacks, but not play passively. I've also tried to 'tune' most of the parameters, to correct what it seems like Crafty could do better (Sometimes passed pawns, etc.). I have also modified the search a little. I've changed the extensions (usually so it will extend more), and I've tried to make it not be so afraid to sacrifice a pawn or the exchange, when it can get good positional gain. I suppose they're mostly tuned against testsuites (Nolot especially), but they seem to play pretty good chess (mostly). They almost always do badly at fast time controls, but I have one version (an older modified 15.20) that plays better than any other Crafty I've seen at fast chess. Perhaps I will someday have official 'versions' of it, but they will always stay 'Modified Crafty x.xx'. Only when I write my own program from scratch someday will I be able to name what I've done. :) I wish I had a Cray, this is not the case. :) I'm running on only a PII-300. Jeremiah
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