Equi-integrable approximation of Sobolev mappings between manifolds

Abstract

We show that limits of sequences of smooth maps between compact Riemannian manifolds with equi-integrable $W^{1,p}$-Sobolev energy can always be strongly approximated by smooth maps, giving a counterpart of Hang's density result in $W^{1,1}$ for the Sobolev space $W^{1,p}$ with integer $p\ge 2$. Our result extends to higher-order Sobolev spaces and is straightforward in fractional Sobolev spaces. We also provide a proof based on the weak continuity of Jacobians in the cases where the cohomological criterion of Bethuel, Demengel, Colon and Hélein applies.

29 pages, minor edits