Author: Tom Kerrigan
Date: 18:02:37 08/26/03
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On August 26, 2003 at 19:34:59, Ricardo Gibert wrote: >On August 26, 2003 at 19:25:39, Steve Maughan wrote: > >>Ricardo, >> >>>"For example I have never used capture searches and rely instead on a static >>>swap off routine." >>> >>>This seems to indicate that CG does not employ a qsearch. I also understand >>>that Junior does something similar. I wonder how this is done? I would >>>presume some type of accuracy tradeoff must be involved, but I wonder what? >>>I'm very curious about how this is all done and why doesn't everybody do it >>>this way? >> >>I guess it's either some sort of SEE or a routine to resolve the effect of >>attack tables. >> >>>How is all the effort that goes into creating a good eval compatible with >>>such a handling of non-quiescent positions? It just seems kind of wacky to me. >> >>It's different - and it clearly did work well in the 80s and 90s. >> >>Regards, >> >>Steve > >It's working pretty well right now in Junior too. > >I haven't been able to find anything on this using google or citeseer. I guess >how to make this work is being kept secret? It would be nice if RL could be >persuaded to reveal this. I don't think this is any secret. I remember reading a BYTE (?) article about the exchange evaluator in early versions of Sargon which they said they used instead of a quiescence search because micros weren't fast enough for the latter. If that was the case for Sargon, I imagine it was also the case for any other program from that era, including predecessors of Fritz, WChess, Genius, and Rebel. Right now there are programs (e.g., HIARCS) with eval terms for en prise pieces which isn't that much of a leap. Another thing is that Genius was very selective, so it may have run its eval function on positions that it considered quiescent through some other means. In practice not much different from a Q search. There may be a trade-off with accracy, but really, the accuracy of Q searches is shit anyway. It may be BETTER to evaluate things as they are than figure that a brain-dead sequence of captures may occur. I've been working on ways to keep my program from returning (inaccurate) evaluations from positions that are very active (e.g., hanging pieces all over) but the Q search decides are legitimate stopping points. Eliminating the Q search doesn't seem like a bad idea at all. -Tom
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