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Re: permutations?

  • To: mathgroup at
  • Subject: [mg46474] Re: [mg46466] permutations?
  • From: "Sseziwa Mukasa,,(978) 536-2359" <mukasa at>
  • Date: Fri, 20 Feb 2004 00:29:18 -0500 (EST)
  • References: <>
  • Sender: owner-wri-mathgroup at

On Feb 19, 2004, at 3:02 AM, sean kim wrote:

> I think this is a permutation problem. but i'm not sure. do correct
> me.

It's not really a permutation problem.  A permutation is a reordering 
of a set without changing elements.  You are substituting new elements 
into the set.


> I have 32 from doing it the brute force way by hand.

If you think about _ and _' as being two states of the same element 
you'll realize you are simply counting in base 2.  ie, abcde=00000 
(base 2)=0 (base 10), abcde'=00001 etc.  You have 5 elements with two 
states each, hence 2^5=32 combinations.

>   how do i do that
> with Mathematica? I don't think it's fully connected graph.  because a 
> only
> connects to downstream b or b'

I'm not sure what you are getting at here.  You could use IntegerDigits 
to generate the binary representation of a number then substitute the 
first element with a or a' depending on whether it's 0 or 1, then the 
second with b or b' etc.

> also... what kinda problem is described above?

It's counting as far as I can tell.



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