simple recursion help

[Thorsten Kampe]

* Hung Jung Lu (2004-11-15 12:12 +0100)
> Thorsten Kampe <thorsten at thorstenkampe.de> wrote:
>> * Hung Jung Lu (2004-10-24 04:16 +0100)
>>> (1) "Variation" is the same as "permutation".
>> 
>> Sorry, no.
> 
> Sorry, yes. 
> 
> Just to add some more information, see also:
> 
> (1) http://en.wikipedia.org/wiki/Combinatorics
> 
> (2) Download user manuals from any major scientific calculator maker
> (HP, Casio, Texas Instruments, Sharp, etc.), and you will find them
> all using the term "permutation" instead of "variation". E.g.:
> 
> http://www.hp.com/calculators/docs/guides/33sProbFact.pdf
> 
> You can promote your preferred term ("variation") as much as you want,
> but to ignore the fact that the majority of people use the term
> "permutation" is a bit strange, to say the least.

It's not "my" preferred term. This guy Guido van Rossum (creator of
the Python language and Benevolent Dictator for Life) uses permutation
in the same sense:
http://www.python.org/doc/current/ref/indentation.html .

And it really isn't possible to use one word (permutation) in one
field (combinatorics) with two totally distinct meanings. If you don't
like "variation" then call it string or "unordered combinations" or
whatever. But please not "permutation". You will confuse everyone
including yourself.

Thorsten