Author: Robert Hyatt
Date: 13:28:39 10/08/02
Go up one level in this thread
On October 08, 2002 at 15:11:56, Uri Blass wrote: >On October 08, 2002 at 14:33:05, Robert Hyatt wrote: > >>On October 08, 2002 at 13:26:52, Uri Blass wrote: >> >>>On October 08, 2002 at 13:16:22, Robert Hyatt wrote: >>> >>>>On October 08, 2002 at 12:22:30, Uri Blass wrote: >>>> >>>>>On October 08, 2002 at 12:10:41, Robert Hyatt wrote: >>>>> >>>>>>On October 08, 2002 at 10:55:29, Uri Blass wrote: >>>>>> >>>>>>>On October 08, 2002 at 10:50:20, Robert Hyatt wrote: >>>>>>> >>>>>>>>On October 08, 2002 at 07:08:51, Uri Blass wrote: >>>>>>>> >>>>>>>>>On October 08, 2002 at 00:52:38, Eugene Nalimov wrote: >>>>>>>>> >>>>>>>>>>Wrong. >>>>>>>>>> >>>>>>>>>>Today I visited the talk by Feng-Hsiung Hsu he gave at Microsoft. Here are some >>>>>>>>>>points from memory: >>>>>>>>>> >>>>>>>>>>They used forward pruning in the hardware, and according to Hsu it gives them >>>>>>>>>>5x-10x speedup. He wrote about that in the book, too, but without any details. >>>>>>>>> >>>>>>>>> >>>>>>>>>Can you ask him if 12(6) really means 12 plies in the software and 6 plies in >>>>>>>>>the hardware? >>>>>>>>> >>>>>>>>>A second question is if the plies in the hardware were selective search from the >>>>>>>>>first ply. >>>>>>>>> >>>>>>>>>>In the talk he named that pruning as "analogy cutoff" and mentioned that "if the >>>>>>>>>>move is useless in some position, it is also useless in the similar position". >>>>>>>>>>In the book he writes "it can be done in the hardware as long as it does not >>>>>>>>>>have to be 100% correct". >>>>>>>>>> >>>>>>>>>>They used null-move thread detection, as well as not only singular extension, >>>>>>>>>>but also extension on only 2 or 3 good replies. They used fractional extensions. >>>>>>>>>>He also says that their Q-search is much more powerful than the one that is >>>>>>>>>>usually used in the software-only programs. >>>>>>>>>> >>>>>>>>>>Hsu gave some details why they don't use null-move: >>>>>>>>>>(1) He thinks that singular extensions and null-move gave more-or-less the same >>>>>>>>>>rating difference (100-200 points IIRC). >>>>>>>>> >>>>>>>>>I think that he underestimates null-move pruning. >>>>>>>>> >>>>>>>>>I believe that for long time control null move pruning gives more than 100-200 >>>>>>>>>points. >>>>>>>>> >>>>>>>>>People may try Fritz with selectivity=0 to find it's rating without null move. >>>>>>>>> >>>>>>>>>Uri >>>>>>>> >>>>>>>> >>>>>>>>I can assure you it doesn't. Several of us ran this experiment in the past. It >>>>>>>>produced a 50-100 >>>>>>>>point improvement at most. Bruce ran it first. I then repeated it to see if >>>>>>>>his result held for me >>>>>>>>as well. 50-100 is nothing to sneeze at of course... But that is all it will >>>>>>>>give... >>>>>>> >>>>>>>What was the time control and the hardware. >>>>>>> >>>>>>>I believe that the improvement is bigger >>>>>>>at slower time control. >>>>>>> >>>>>>>If the experiment was some years ago and >>>>>>>in time control that is faster than 120/40 >>>>>>>then the results may be different today. >>>>>>> >>>>>>>Uri >>>>>> >>>>>> >>>>>>I don't know about Bruce. I used 40 moves in one hour followed by 20 moves in >>>>>>30 minutes, >>>>>>with no sudden-death at all. >>>>>> >>>>>>I ran it on several computers here for several weeks... >>>>> >>>>>We have a factor of 2 in the time control. >>>>> >>>>>What was the hardware that was used? >>>>>If the games were played 5 years ago then today we have clearly >>>>>faster hardware. >>>>> >>>>>Uri >>>> >>>> >>>>Pentium pro 200's. I played 2 games at a time on my quad, plus more games in a >>>>linux lab we >>>>had set up. >>>> >>>>yes hardware is faster. No I don't believe that going deeper and deeper >>>>eliminates all the problems >>>>with null-move. I only saw bad problems at depths of 5-6-7-8. I _never_ saw >>>>them pop up at >>>>depths of 12 and beyond, which Crafty could reach in the pentium pro at 1 minute >>>>a move... >>>> >>>>R=2 used to gain at most 2 plies. Yet the overall performance improvement from >>>>my testing >>>>was in the 50-60 point range. Far less than what you would normally expect from >>>>gaining 2 >>>>plies. The conclusion? You aren't _really_ gaining two plies of search depth, >>>>just two plies >>>>reported in the output... >>> >>>I did not say that you get 2 plies of search depth from 2 plies of output but >>>only that I believe that the difference is bigger than 100-200. >>> >>>It may be interesting to repeat the experiment today >>>(you use R=2/3 and not R=2 and it is also important). >>> >>>Uri >> >> >> >>OK... that means that you think that a null-mover will win 3 of every 4 games >>vs a non-null-mover, >>_everything_ else being the same? >> >>I can run that test. >> >>I'll let you pick the time control. Pick something that xboard/winboard will >>like and I'll fire it up on >>a quad and let it play two games at a time using one processor for each side) >>for a while... >> >>How about 40 moves every 60 minutes or something similar, repeated until the >>game is drawn or >>ends normally... > >I guess that even Crafty(R=3) is good enough to get 75% at 60 minutes/40 moves >against Crafty(R=0) (I think that programs that do checks in the qsearch like >Tao can get even better results). > >My guess is based on my experience with movei when my results suggest that the >latest movei earn more from time relative to the public movei when one of the >differences is that I use R=3 in the latest version when the public version is >using R=2. > >I admit that I did not do comparison of only R=2 against R=3 except test suites >when R=3 scored better. > >Uri OK. I have a quad free and am playing two games at a time using two copies of xboard, one crafty has normal null-move (2/3) the other has none (sel=0/0). I will report as I get results...
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