Author: Robert Hyatt
Date: 09:10:41 10/08/02
Go up one level in this thread
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...
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