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Gmane
From: Jesus M. Castagnetto <jcastagnetto <at> yahoo.com>
Subject: Re: [PEPr] Comment on Math::Math_Combinatorics
Newsgroups: gmane.comp.php.pear.devel
Date: Sunday 1st April 2007 15:33:33 UTC (over 9 years ago)
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  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
> 
> -- 
> PEAR Development Mailing List (http://pear.php.net/)
> To unsubscribe, visit: http://www.php.net/unsub.php
> 
> 


--
Jesus M. Castagnetto ([email protected])
Web site: http://www.castagnetto.org/
Research: http://metallo.scripps.edu/
PEAR stuff: http://pear.php.net/user/jmcastagnetto


 
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