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

Author: Ricardo Gibert

Date: 16:57:11 05/31/05

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On May 31, 2005 at 14:28:46, Robert Hyatt wrote:

>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).

Aha! I understand my error now. I'm thinking of something like average branching
factor. EBF looks like BS with things like extensions, qsearch, etc. taking
place in programs. A misleading stat at best.

>
>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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