On Sat, Apr 12, 2014 at 07:40:05AM -0700, Matthew Rocklin wrote:
>    In sympy/core/sets.py:
> 
>  > @@ -1247,6 +1279,9 @@ def __iter__(self):
>  >      def _eval_imageset(self, f):
>  >          return self
>  >
>  > +    def _eval_powerset(self):
>  > +        return FiniteSet([self])
> 
>    Is this mathematically correct? What is the powerset of the emptyset ? It

Yes.  See the reference.