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Subject: Re: How is Hydra faster and better than Deep Blue?

Author: Robert Hyatt

Date: 11:28:46 05/31/05

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On May 31, 2005 at 09:46:53, Gian-Carlo Pascutto wrote:

>On May 31, 2005 at 01:21:54, Eugene Nalimov wrote:
>
>>>By this redefinition of EBF, I don't immediately see how any technique *can*
>>>have any effect on the EBF.
>>
>>Any technique that changes shape of the tree can easily cause change of the >EBF.
>
>Did you actually read the thread? He seems to be talking about some "other kind
>of EBF" where that does not happen. I can't explain it in any other way.
>
>>And now think about SE in particular. Without SE you can stop searching the node
>>the moment you have cutoff. With SE you should search further, thus increasing
>>EBF. [Of course you are searching extra subtrees, and those subtrees should
>>affect EBF, too, though I don't know what way].
>
>Which is exactly what I and Robert have been saying...
>
>--
>GCP

I think that the confusion lies in that the EBF is usually computed as
time(ply)/time(ply-1).  Where the real EBF could be considered the sum of the
moves searched at all nodes that are expanded, divided by the number of nodes
that were expanded (an average branching factor, more or less).

I have just come to the conclusion that the term "ply" only means something
useful within my own program.  Comparing it to other programs is not very useful
since the depth reached is the sum of a lot of other things inside the program,
from extensions and how much they extend, to repeated searches for things like
SE, etc...






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