Consider the following:
For any smooth Jordan curve $\gamma\subset D$, where $D$ is simply connected, we can find a smooth surface $\Sigma \subset D$ such that $\partial\Sigma = \gamma$.
I am curious about the validity of the statement and how could one possibly go about proving it with more rigour rather than intuition. This was used in a proof that if the vector field is irrotational and the domain is simply connected then it is integrable. Just stating it felt very hand-wavy
Thank you for any suggestions or ideas!