Author: Robert Hyatt
Date: 18:43:47 07/07/02
Go up one level in this thread
On July 07, 2002 at 16:47:33, Omid David wrote: >On July 07, 2002 at 16:36:57, Robert Hyatt wrote: > >>On July 07, 2002 at 11:48:27, Omid David wrote: >> >>>On July 06, 2002 at 23:23:28, Robert Hyatt wrote: >>> >>>>On July 06, 2002 at 22:29:44, Omid David wrote: >>>> >>>>>On July 06, 2002 at 10:20:17, Robert Hyatt wrote: >>>>> >>>>>>On July 06, 2002 at 01:07:36, Ricardo Gibert wrote: >>>>>> >>>>>>> >>>>>>>Okay, but so what? >>>>>>> >>>>>>>> >>>>>>>>So perhaps the idea of "forward pruning" is foreign to us as well... >>>>>>> >>>>>>>I see no logical difference between deciding which moves are interesting and >>>>>>>worth looking at and deciding which moves are not interesting and not worth >>>>>>>looking at. It looks to me like 2 sides of the same coin, so your speculation >>>>>>>that "perhaps the idea of "forward pruning" is foreign to us as well..." does >>>>>>>not seem to be of any consequence. >>>>>>> >>>>>> >>>>>>However, that has been _the point_ of this entire thread: Is DB's search >>>>>>inferior because it does lots of extensions, but no forward pruning. I >>>>>>simply said "no, the two can be 100% equivalent". >>>>> >>>>>Just a quick point: The last winner of WCCC which *didn't* use forward pruning >>>>>was Deep Thought in 1989. Since then, forward pruning programs won all WCCC >>>>>championships... >>>> >>>> >>>>In 1992 no "supercomputer" played. In 1995 deep thought had bad luck and lost >>>>a game it probably wouldn't have lost had it been replayed 20 times. No >>>>"supercomputer" (those are the programs that likely relied more on extensions >>>>than on forward pruning due to the hardware horsepower they had) has played >>>>since 1995... >>>> >>>>I'm not sure that means a lot, however. IE I don't think that in 1995 fritz >>>>was a wild forward pruner either unless you include null move. Then you >>>>would have to include a bunch of supercomputer programs including Cray Blitz >>>>as almost all of us used null-move... >>> >>>I personally consider null-move pruning a form of forward pruning, at least with >>>R > 1. I believe Cray Blitz used R = 1 at that time, right? >> >> >>I believe that at that point (1989) everybody was using null-move with R=1. >>It is certainly a form of forward pruning, by effect. > >Yes, and today most programs use at least R=2... The fact is that new ideas in >null-move pruning didn't cause this change of attitude, just programmers >accepted taking more risks! I think it is more hardware related. Murray Campbell mentioned R=2 in the first null-move paper I ever read. He tested with R=1, but mentioned that R=2 "needs to be tested". I think R=2 at 1980's speeds would absolutely kill micros. It might even kill some supercomputers. Once the raw depth with R=2 hits 11-12 plies minimum, the errors begin to disappear and it starts to play reasonably. But at 5-6-7 plies, forget about it.
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