There are often questions in differential geometry asking if a certain manifold (say a circle) has a polynomial parametrization. Are there topological obstructions to existence of such parametrization? More precisely, if we have a polynomial map $f:U\rightarrow R^m$ (and suppose $U$ is the interior of a cube in $\mathbb{R}^n$), then
$\bullet$ can the image of $f$ have non-trivial topology? I'm guessing the answer is yes but can't think of an example.