Author: Uri Blass
Date: 04:08:51 10/08/02
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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
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