Author: David Rasmussen
Date: 17:11:27 12/13/01
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On December 13, 2001 at 18:15:57, Robert Hyatt wrote: >On December 13, 2001 at 17:15:16, David Rasmussen wrote: > >>It has been "proved" that a two-level table with one table being depth >>prioritized (I don't remember how many percent of the table that should be depth >>prioritized, optimally). Crafty uses this approach, with 1/3 being DP, if I >>remember correctly. I think it was in Brucker's thesis about hashing in game >>trees. >> >>/David > > >"proved" is too strong a word. multiple probes (2 or more) certainly reduce Ok, I meant ""proved"", then :) >the size of the tree. But they also have a fixed cost associated with them >(they consume memory bandwidth that is already scarce). 2-level is a >compromise between (a) using more bandwidth and going slower and (b) doing >only one probe which will make the tree a bit larger. > >Smaller trees are good, so long as the total search time is also smaller. If >you spend _too_ much time reducing the size of the tree, the cost of reducing >the tree size may well exceed the savings caused by searching a smaller space. I know it's a design choice and a compromise either way. But Breuker tested a lot of different setups, number of probes, number of tables, depth prioritized etc. etc. And he """proved""" that in general, the scheme that you use, actually, is the """""best""""". /David
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