The $L^2$-unique continuation property on manifolds with bounded geometry and the deformation operator

Abstract: A differential operator $T$ satisfies the $L<sup>2$-unique continuation property if every $L<sup>2$-solution of $T$ that vanishes on an open subset vanishes identically. We study the $L<sup>2$-unique continuation property of an operator $T$ acting on a manifold with bounded geometry. In particular, we establish some connections between this property and the regularity properties of $T$. As an application, we prove that the deformation operator on a manifold with bounded geometry satisfies regularity and $L<sup>2$-unique continuation properties. As another application, we prove that suitable elliptic operators are invertible (Hadamard well-posedness). Our results apply to compact manifolds, which have bounded geometry.