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Re: A Question about Combinatorica

  • To: mathgroup at smc.vnet.net
  • Subject: [mg102684] Re: [mg102627] A Question about Combinatorica
  • From: Murray Eisenberg <murray at math.umass.edu>
  • Date: Tue, 18 Aug 2009 06:11:01 -0400 (EDT)
  • Organization: Mathematics & Statistics, Univ. of Mass./Amherst
  • References: <200908170804.EAA27022@smc.vnet.net>
  • Reply-to: murray at math.umass.edu

Sorry, but your questions is unclear.  There are 5!, that is, 120, 
permutations of a list of length 5. And that is what Permutations and 
Combinatorica`MinimumChangePermutations` both give you.

What does 60 have to do with it?

Marwa Abd El-Wahaab wrote:
> Dear Sir,
> I have a question about having five letters like {A, B, C, D, E}. In order
> to get all possibilities, we have 5! possible cases like ABCDE,
> EABCD,.......etc
> 
> The number of these possibilities are 120. How and why this number becomes
>  60 by dividing by 2 ?
> 
> What are 60 possibilities & how extract them from 120?
> 
> I used this function to get 120:
> 
> MinimumChangePermutations[{A,B,C,D,E}]
> 
>  What should I do after this to get 60?
> 
> Thanks too much
> 
> I really need your help
> 
> *Marwa Ali Abd El Wahaab*
> *Teaching Assistant*
> Faculty of Engineering
> Mansoura University
> 
> 

-- 
Murray Eisenberg                     murray at math.umass.edu
Mathematics & Statistics Dept.
Lederle Graduate Research Tower      phone 413 549-1020 (H)
University of Massachusetts                413 545-2859 (W)
710 North Pleasant Street            fax   413 545-1801
Amherst, MA 01003-9305


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