Returning unevaluated ImageSets makes sense.  So too does raising
NotImplementedErrors.  I don't have thoughts about which is best.


On Thu, Feb 13, 2014 at 2:36 AM, Sergey B Kirpichev <
notifications@github.com> wrote:

> In sympy/sets/fancysets.py:
>
> > @@ -219,6 +219,26 @@ def _contains(self, other):
> >                      return True
> >          return False
> >
> > +    def _intersect(self, other):
> > +        from sympy import solve, Dummy, imageset
> > +
> > +        if isinstance(other, ImageSet):
> > +            return
>
> Nice. Why we can't just return an unevaluated ImageSet in the
> Interval._eval_imageset (see #2723<https://github.com/sympy/sympy/pull/2723>
> ).
>
> @mrocklin <https://github.com/mrocklin>, does this make sense?
>
> --
> Reply to this email directly or view it on GitHub<https://github.com/sympy/sympy/pull/2904/files#r9704522>
> .
>