Author: Robert Hyatt
Date: 13:06:38 05/30/05
Go up one level in this thread
On May 30, 2005 at 07:23:24, Ricardo Gibert wrote: >On May 30, 2005 at 06:21:14, Pallav Nawani wrote: > >>On May 30, 2005 at 02:02:49, Amir wrote: >> >>>Deep Blue could calculate 200 million moves per second. According to what I have >>>read, Hydra calculates 40 million moves per second. How then is Hydra sees >>>deeper or is faster than Deep Blue, as is claimed by the authors?? >> >>According to the logs that I saw, deep blue was searching 12 plies deep in the >>K-DB match. My program can match that depth on a 1.1Ghz PC. This is because of >>search techniques that were not used in deep blue. Eg: Null move, Rebel style >>reductions, aggressive pruning. Hydra is obviously using such search techniques, >>and given its higher processing power, it will easily outsearch Deep Blue. In >>fact, in Shredder-Hydra match, shredder was searching to 16 ply (I think, but I >>could be wrong) which was almost the same as Hydra (Again, not sure). >> >>Also, Deep Blue was using Singular Extensions, which increases the number of >>nodes required in search. > >But which also reduces EBF. You should have left out this paragraph. No. In fact it increases it significantly. In Cray Blitz, it reduced our average search depth about 2 plies. Which is a significant _increase_ in effective branching factor. > >> >>Also note that 9 plies of program 1 are not the same as 9 plies of program 2. >>These programs may be using different search techniques/extensions etc, and >>therefore on basis of plies searched you cannot guess the relative strength of >>programs. For instance, singular extensions are reputed to increase tactical >>strength quite a bit, but they may decrease the depth of search. >> >>Pallav > >I better though still imperfect comparison uses: > >effective_depth = log(nodes)/log(EBF) > >If given 2 programs where one reports a lower depth, because it does a lot of >extentions and another that reports a higher depth, because it does a lot of >pruning, but they otherwise generate the same search tree, then the above will >return the same effective_depth. log(EBF) is diluting the calculation. "nodes" is already included in EBF.
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