Hi Rob!

(CC to sage-combinat; this is thread [1] on sage-devel)

On Tue, Sep 04, 2012 at 07:36:51AM -0700, Rob Beezer wrote:
>    On Tuesday, September 4, 2012 6:21:11 AM UTC-7, John Cremona wrote:
> 
>      If pi is a permutation, e.g. defined by pi=permutations(4)[3], then
>      pi.signature() returns what I have always called the "sign" of pi, and
>      none of pi.sign(), pi.sgn(), sign(pi), sgn(pi) work.
> 
>    But:
> 
>    sage: G = SymmetricGroup(2)
>    sage: a = G("(1,2)")
>    sage: a.sign()
>    -1
> 
>    So I'd say +1 to greater coordination between group element permutations
>    and purely combinatorial permutations overall, and in particular having 
>    .sign()  as John suggests for the "other" permutations.

+1! This miscoordination has been an itch for us for quite a while.
In general, Permutations need some heavy refactoring which will be
best done all at once; but a simple change like this can be done right
away.

Cheers,
                                Nicolas

PS: 
https://groups.google.com/forum/?hl=fr&fromgroups=#!topic/sage-devel/DYVbTWWOMtE)
--
Nicolas M. ThiƩry "Isil" <nthi...@users.sf.net>
http://Nicolas.Thiery.name/

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