MathGroup Archive 2004

[Date Index] [Thread Index] [Author Index]

Search the Archive

Re: permutations?


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.

[deleted]

> 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.

Regards,

Ssezi


  • Prev by Date: Re: permutations?
  • Next by Date: Re: Help Browser issue in 5.0.1 on Mac OS X
  • Previous by thread: permutations?
  • Next by thread: Re: permutations?