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Subject: Re: Search algorithms

Author: Robert Hyatt

Date: 19:42:14 11/06/03

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On November 06, 2003 at 22:33:04, Robert Hyatt wrote:

>On November 06, 2003 at 20:45:57, Dave Gomboc wrote:
>
>>On November 06, 2003 at 19:50:09, Robert Hyatt wrote:
>>
>>>On November 06, 2003 at 11:23:36, Dave Gomboc wrote:
>>>
>>>>On November 06, 2003 at 09:49:33, Robert Hyatt wrote:
>>>>
>>>>>On November 06, 2003 at 09:33:28, Renze Steenhuisen 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.
>>>>>>
>>>>>>Done that already, but as Aske stated: they search the same nodes, but in a
>>>>>>different order.
>>>>>>
>>>>>>MTD(f) and the others are still DF algorithms, the second list works differently
>>>>>>(i.e., the order in which the nodes are expanded is different).
>>>>>>
>>>>>>Or am I talking rubish?
>>>>>>
>>>>>>Renze
>>>>>>
>>>>>>PS:  Am I missing algorithms (either important or not)?
>>>>>>PS2: Are Scout and NegaScout equal?
>>>>>
>>>>>
>>>>>They are just variations on the same idea.  All fall under the umbrella
>>>>>of alpha/beta depth-first search...  (this is in response to your question
>>>>>PS2).
>>>>>
>>>>>depth-first and breadth-first (best-first is one example of the latter)
>>>>>are totally unrelated other than the fact they both search a tree.
>>>>
>>>>Well, no.  Read Plaat's thesis.
>>>>
>>>>Dave
>>>
>>>
>>>I have read it.  It does _not_ say the two are equivalent in any shape
>>>or form, except for the actual tree searched in certain circumstances.
>>>Depth-first and breadth-first are completely different approaches to
>>>growing a tree, even if on some occasions they grow the _same_ tree.
>>
>>In this particular case, the algorithms search the same tree.  Therefore, I
>>think it's reasonable to claim they are they are equivalent in some shape or
>>form -- not in all shapes and all forms, but at list with respect to the nodes
>>searched and the order in which they are searched. :-)
>>
>>Dave
>
>
>I don't believe that last is correct. IE with respect to order.  Particularly
>comparing members of the breadth-first family to the depth-first family and
>not just picking one specific algorithm from each.


BTW,  I hope you don't try to convince me all sort algorithms are
equivalent, just because they take the same list and produce the
same final result.  :)




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