Author: Uri Blass
Date: 07:55:29 10/08/02
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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
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