Author: Dann Corbit
Date: 21:05:25 09/05/02
Go up one level in this thread
On September 05, 2002 at 23:44:54, Robert Hyatt wrote:
[snip]
>That is the point. Super-linear speedup is a direct proof of bad move
>ordering, as that is the only way to get one. I get a few (I am going to
>post a set of positions for Martin in just a few minutes) but those are
>offset (more than offset actually) by less than linear speedups in other
>positions...
Improved move ordering is one way to get more than linear speedup. But I think
that there may be others.
Consider chasing the pv with one of the CPU's. As long as you have the move
ordering perfect, and you are not running down a blind canyon, you might
(should) be getting improvement for each forward ply of the pv. Now, as the
second (or nth or whatever) CPU chases along the PV and analyzes, it fills the
hash table with goodies about the future. Some other searches will see this
{far into the future} data and instead of a ce of +0.2 it is a ce of +1.4. This
causes all the poor searches to cut off much more easily. Perhaps it can reduce
the tree to 1/10 of its former size.
So what I am suggesting is that some *other* searching method than a "brute
expansion of the a/b search tree by labor division" might shrink the tree. And
not just by move ordering but also by improved cutoffs.
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