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A Question about Combinatorica

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  • Subject: [mg102627] A Question about Combinatorica
  • From: Marwa Abd El-Wahaab <m.a.elwahaab at>
  • Date: Mon, 17 Aug 2009 04:04:09 -0400 (EDT)

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,

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:


 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

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