Re: [PEPr] Comment on Math::Math_Combinatorics
| From: | Jesus M. Castagnetto | Date: | Sun, 01 Apr 2007 15:33:33 +0000 |
| Subject: | Re: [PEPr] Comment on Math::Math_Combinatorics | ||
| References: | 1 | Groups: | php.pear.dev |
| Request: | Send a blank email to pear-dev+get-46124@lists.php.net to get a copy of this message | ||
Just as a reference. For combinations and permutations there exist some other
variations, for example the "Complete Permutation" (or Derangement), and such
other weirdness.
See:
http://mathworld.wolfram.com/Permutation.html
http://mathworld.wolfram.com/Derangement.html
http://mathworld.wolfram.com/AlternatingPermutation.html
http://mathworld.wolfram.com/CircularPermutation.html
http://mathworld.wolfram.com/Combination.html
http://mathworld.wolfram.com/BinomialCoefficient.html
... etc.
Caveat: I had not looked in detail at your package. My net connection right now
is quite flaky.
Cheers.
--- David Sanders <dsanders@baselinesolutions.com.au> wrote:
>
> I was thinking more of having repitition as an option. Wiki *said* the
> definition can be either with or without repitition for both combinations
> and permutations. (Now this is what I don't like about wiki: Someone has
> deleted the "Permutations without Repitition" sub-section without even
> providing a reason. See the history tab)
>
>
> >
> > However, there's a topic to think about - repetitions. The original
> > definition of combination in mathematics implies that the elements have
> > to be unique, i.e. the combinations of the set {A, A, B} are the same as
> > these of {A, B}, of {A, A, A, A, B}, etc. Nevertheless, the term
> > "combination with repetition" exists. I will try to take a look in my
> > university courses on combinatorics during the weekend, because I'm
> > uncertain what is the correct behaviour that has to be followed in the
> > package.
> >
>
>
> --
> David Sanders
> shangxiao
>
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>
--
Jesus M. Castagnetto (jcastagnetto@yahoo.com)
Web site: http://www.castagnetto.org/
Research: http://metallo.scripps.edu/
PEAR stuff: http://pear.php.net/user/jmcastagnetto
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