Author: Ralf Elvsén
Date: 02:47:34 07/20/00
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On July 19, 2000 at 22:18:53, Peter Kappler wrote: >On July 19, 2000 at 20:14:20, Ralf Elvsén wrote: > >>On July 19, 2000 at 18:13:30, Peter Kappler wrote: >> >>>On July 19, 2000 at 17:56:44, Larry Griffiths wrote: >>> >>>>Hi, >>>> >>>>I have been re-programming my chess engine lately and have been implementing a >>>>concept that I saw posted here about a year ago. >>>> >>>>The concept is to look out from the FROM and TO squares when a piece is moved to >>>>determine what pieces need to have their moves re-generated. >>>> >>>>I am having second thoughts about this since it is about equal to >>>>generating moves for 2 Queens, 2 Kings, 2 Knights and 2 Pawns looking out >>>>from the FROM and TO squares. >>>> >>>>Is anybody using something like this, or even tried this? >>>> >>>>Larry >>> >>> >>>A couple of months ago, I seriously considered scrapping my move generator and >>>using an incremental scheme, like the one you described. I spent a couple of >>>nights thinking about the design, and then decided it was too much work. :) >>> >>>The big advantage I see is that you automatically get up-to-date attack >>>information, which is extremely valuable in an eval function. >>> >>>I asked Bob about this a long time ago, and he said he started down this path >>>with Crafty before switching to bitboards. I also think KnightCap does >>>incremental move generation, and the source code is available. >>> >>>--Peter >> >>For fun I wrote a (almost) full OO-chess program in Java with this >>move generation. It worked but was sloooooooooow, but that was only >>one of many reasons :) >> >>Ralf > > >Mine is in Java, too! :) > >--Peter Yes, I know. And you seem to have a pretty strong program with competitive speed (whatever that means). I wrote a more serious Javaprogram but I never got any speed (or depth rather) out of it. It's not Java's fault, you have proved that. But I never could figure out where the problem was, in spite of tweaking and profiling. Since I was in a position where I could use some C-knowledge in other situations, I started porting the program to C, to learn the language better (unfinished project). Lately I have begun to suspect that the try/catch statements in my Javacode was partly responsible for the preformance. Do you know if this is true? Can you guesstimate other pitfalls for an unexperienced Java-chess programmer? I like Javaprogramming though. If they ever add genericity and maybe covariance and some other "minor" improvements, it will be a joy :) Ralf
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