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Subject: Re: Search algorithms

Author: Robert Hyatt

Date: 19:31:49 11/06/03

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On November 06, 2003 at 20:43:58, Dave Gomboc wrote:

>On November 06, 2003 at 19:46:29, Robert Hyatt wrote:
>
>>On November 06, 2003 at 11:22:54, Dave Gomboc wrote:
>>
>>>On November 06, 2003 at 09:47:32, Robert Hyatt wrote:
>>>
>>>>On November 06, 2003 at 08:33:49, Gian-Carlo Pascutto wrote:
>>>>
>>>>>On November 06, 2003 at 05:45:53, Renze Steenhuisen wrote:
>>>>>
>>>>>>Depth-First Algorithms:
>>>>>>  AlphaBeta (Fail-hard, Fail-Soft)
>>>>>>  MTD(f)
>>>>>>
>>>>>>Best-First Algorithms:
>>>>>>  SSS*
>>>>>
>>>>>The distinction between the three (and best-first and depth-first)
>>>>>is very hazy, read "Research re: search and research" by Aske Plaat.
>>>>>
>>>>>--
>>>>>GCP
>>>>
>>>>
>>>>Eh?  The distinction is _huge_.
>>>>
>>>>One searches the tree in one direction and requires very little memory.  The
>>>>other searches the tree in another direction and requires huge memory.
>>>>
>>>>I'm not sure how you could say that the distinction is very hazy.  They
>>>>are as different as night and day...
>>>
>>>However, MTD(infinity) is equivalent to (searches exactly the same tree as) SSS.
>>
>>
>>That's fine.  A best-first (breadth-first) search can search _exactly_
>>the same tree as a minimax (depth-first) search also.  Doesn't mean a
>>thing about how similar the two approaches are, however...
>>
>>However, the trees are grown differently.    I don't think any book I
>>know of uses the actual search space as a way to define a search
>>strategy...
>>
>>
>>>
>>>http://www.cs.ualberta.ca/~jonathan/Grad/plaat.phd.ps
>>>
>>>Dave
>
>Fine, but the point is that in this particular case, they are not as different
>as night and day. :-)
>
>Dave

They are different in the base algorithm.  They are different in their
memory requirements.  They are different in the order in which they search
the tree.  They are different in how hashing may (or may not) work.

Other than that, they are the same.  :)

Sort of like the old "yeah I knew him, we went to different schools together."





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