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Subject: Re: Big-O notation

Author: Ricardo Gibert

Date: 10:57:06 05/09/01

Go up one level in this thread


On May 09, 2001 at 13:37:58, Uri Blass wrote:

>On May 09, 2001 at 13:23:25, Dann Corbit wrote:
>
>>On May 09, 2001 at 13:18:52, Uri Blass wrote:
>>
>>>On May 09, 2001 at 11:27:46, Dann Corbit wrote:
>>>
>>>>On May 09, 2001 at 10:12:30, Ricardo Gibert wrote:
>>>>
>>>>>On May 09, 2001 at 02:00:25, Dann Corbit wrote:
>>>>>
>>>>>>For those of you who don't want to perform your own web search, just choose one
>>>>>>of these:
>>>>>>
>>>>>>http://hissa.nist.gov/dads/HTML/bigOnotation.html
>>>>>>http://bio5495.wustl.edu/textbook-html/node15.html
>>>>>>http://umastr.math.umass.edu/~holden/Math136-99_projects/Amstutz-OBoyle-Petravage/big-o.html
>>>>>>http://www.eecs.harvard.edu/~ellard/Q-97/HTML/root/node8.html
>>>>>>http://classes.monterey.edu/CST/CST338-01/world/BigO.html
>>>>>>http://shalim.csustan.edu/~john/Classes/CS3100_DataStructures/Previous_Semesters/1999_04_Fall/Examples/big-O
>>>>>>
>>>>>>CS:201, FCOL!
>>>>>
>>>>>Big-O notation is used to describe asymtotic behavior. It commonly used to
>>>>>describe the "running time" of an algorithm. If an algorithm is O(f(n)), n is
>>>>>understood to be a finite, but *unbounded*. (For some reason, "unbounded" gets
>>>>>confused with infinity. This is an error, but let's not get into that. It isn't
>>>>>relevant here)
>>>>>
>>>>>In chess, n in is bounded. This is a critical distinction, that means chess is
>>>>>*not* NP.
>>>>
>>>>GREAT!  Then it's computable.  What's the answer, win-loss-draw?
>>>>;-)
>>>
>>>I see no point in continuing to argue.
>>>The question is simply question of definition.
>>>I did not say that it is easy to solve.
>>>
>>>I use the definition of NP only for problems with n that is not bounded
>>>otherwise the mathematical definition say that it is O(1)(there is a constant
>>>and the only problem is that it is too large)
>>>
>>>I can agree that chess is practically O(exp(n)) and not polynomial for practical
>>>purposes but it does not change the fact that by mathematical definition it is
>>>O(1).
>>
>>This is simply wrong.  I guess we are at an impasse.
>>
>>>You can say that Sorting is also O(1) from theoretical point of view if you look
>>>at sorting that is done by a computer.
>>
>>Show me any algorithms book that says any sorting algorithm is O(1).
>
>The sorting from theoretical point of view is not O(1) because the size of the
>input is not bounded.
>Sorting done by a computer has bounded size and every problem of bounded size is
>O(1) by the definition that I know.
>
>A problem can be O(n) only if n is not bounded by a finite bound by the
>definition that I use.
>
>I look at sorting from mathematical point of view and not from computer point of
>view and this is the reason that I said that it is not O(1).
>
>Uri

It's a lost cause. he keeps comparing apples with oranges. In chess n is a
constant. In a sorting algorithm it is unbounded. Hopeless.



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