Author: Robert Hyatt
Date: 20:53:16 07/07/02
Go up one level in this thread
On July 07, 2002 at 23:42:03, Omid David wrote: >On July 07, 2002 at 21:43:47, Robert Hyatt wrote: > >>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. > >So using a fixed R=3 seems to be possible in near future with faster hardware, >doesn't it? Very possibly. Or perhaps going from 2~3 as I do now to 3~4 or even 4~5 for all I know... I should say that going from 2 to 3 is not a huge change. Bruce and I ran a match a few years ago with him using Ferret vs Crafty with Ferret using pure R=2, and then pure R=3. We didn't notice any particular difference at that time. It played about the same, searched about the same depth, etc...
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