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

Author: Tony Werten

Date: 22:47:12 05/31/05

Go up one level in this thread


On May 31, 2005 at 20:31:38, Robert Hyatt wrote:

>On May 31, 2005 at 15:32:25, Gian-Carlo Pascutto wrote:
>
>>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).
>>
>>No, because in both definitions an extension would behave as we normally expect,
>>i.e. always increases BF.
>
>No.  Think about it for a minute.  It doesn't affect "the average moves per
>node" whatsoever.  It just drives the search deeper along certain paths...  Even
>if you do the DB/CB SE approach, the SE detection searches don't change the
>"average branching factor" at all, as each node will still have about the same
>number of moves to search...
>
>I think that is what is causing the confusion here.

No, I think the confusion is that GC leaves the word "effective" out every now
and then :) but I'm pretty sure he's only talking about ebf.

Tony




>
>
>
>>
>>The original poster had some kind of idea of "average depth" in mind but we
>>don't usually consider that.
>>
>>--
>>GCP



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