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

Author: Uri Blass

Date: 05:05:17 06/01/05

Go up one level in this thread


On June 01, 2005 at 07:16:30, Gian-Carlo Pascutto wrote:

>On June 01, 2005 at 05:54:53, Uri Blass wrote:
>
>>On June 01, 2005 at 04:57:59, Gian-Carlo Pascutto wrote:
>>
>>>On June 01, 2005 at 01:47:12, Tony Werten wrote:
>>>
>>>>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.
>>>>
>>>
>>>Yes. But the distinction between both is pretty irrelevant for the point, which
>>>was that Ricardo is using some defintion of branching factor which is totally
>>>not the same as what is normally used (both effective and real), and then used
>>>that to say "you are wrong". Another claim was that one can infer the 'goodness'
>>>of an extension by it's effect on the branching factor (any kind).
>>>
>>>Both make no sense, and the first one will additionally lead to a lot of
>>>confusion.
>>>
>>>That is now quite sufficiently proven, I think :-P
>>>
>>>Thinking of it, there are some extensions that will decrease the "true"
>>>branching factor (as we normally understand it). Check extensions, for example.
>>>
>>>--
>>>GCP
>>
>>I do not see it.
>>
>>Check extensions only increase the branching factor(in other words the program
>>need more time to get the same depth)
>
>Uri, most of this thread revolves about discussion about what the "branching
>factor" is. I suggest you try to deduce the *meaning intended* first before
>replying, instead of jumping in and missing the bat completely.
>
>Look at Robert's post for a hint.
>
>--
>GCP

You wrote
"will decrease the "true" branching factor (as we normally understand it). in
your post.

I understood earlier that the discussion is about something that is not
considered to be the branching factor by most readers so I stayed out of this
discussion but when you wrote
"as we normally understand it" I thought that the discussion is irrelevant
and you talk about what most people understand as true branching factor.


Uri



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