[sage-support] Symmetric variables in a polynomial

[Jori Mantysalo]

Is there easy way to get "variables group" of a polynomial, or a list of 
interchangeable variables? I.e. from

a*b+c
one would get

[[a,b]]

or from

a*b+c*d

either

[[a,b],[c,d]]

or a group isomorphic to D_4.

--
Jori Mäntysalo