I posted this question a few days ago to https://or.stackexchange.com/questions/13173/optimization-over-loop-spaces but didn't receive any replies, so I thought I would try here (if this is improper then I apologize!):
Has anyone written any deep work about infinite-dimensional optimization over "loop spaces", i.e. the space of simple closed curves in (say) $\mathbb{R}^2$? Of course, one could simply consider the parameterization $f(t):[0,1]\to\mathbb{R}^2$ subject to the constraint that $f(0)=f(1)$, but I'm curious if there is anything we can say about regarding these objects independently of their parameterization; for instance, the Euclidean TSP on points $\{p_1,\dots,p_n\}$ becomes $\min_L\mathrm{length}(L)$ subject to the constraint that $p_i\in L$ for all $i$. A related concept would be taking the set of convex shapes in the plane, with addition defined via Minkowski sums, but things clearly become more challenging when one relaxes the convexity requirement.