arXiv subjects

Tony Liimatainen

Publications and source records attributed to Tony Liimatainen.

40 records · Page 3Linked to original sources

arXiv2013

On the Role of Riemannian Metrics in Conformal and Quasiconformal Geometry

This article is the introductory part of authors PhD thesis. The article presents a new coordinate invariant definition of quasiregular and quasiconformal mappings on Riemannian manifolds that generalizes the definition of quasiregular mappings on $\R^n$. The new definition arises naturally from the inner product structures of Riemannian manifolds. The basic properties of the mappings satisfying the new definition and a natural convergence theorem for these mappings are given. These results are applied in a subsequent paper, arXiv:1209.1285. In the current article, an application, likewise demonstrating the usability of the new definition, is given. It is proven that any countable quasiconformal group on a general Riemannian manifolds admits an invariant conformal structure. This result generalizes a classical result by Pekka Tukia in the countable case.

math.DG↗

arXiv2013

Local gauge conditions for ellipticity in conformal geometry

In this article we introduce local gauge conditions under which many curvature tensors appearing in conformal geometry, such as the Weyl, Cotton, Bach, and Fefferman-Graham obstruction tensors, become elliptic operators. The gauge conditions amount to fixing an $n$-harmonic coordinate system and normalizing the determinant of the metric. We also give corresponding elliptic regularity results and characterizations of local conformal flatness in low regularity settings.

math.DG↗

arXiv2012

Optimal Riemannian metric for a volumorphism and a mean ergodic theorem in complete global Alexandrov nonpositively curved spaces

In this paper we give a natural condition for when a volumorphism on a Riemannian manifold $(M,g)$ is actually an isometry with respect to some other, optimal, Riemannian metric $h$. We consider the natural action of volumorphisms on the space $\M_μ^s$ of all Riemannian metrics of Sobolev class $H^s$, $s>n/2$, with a fixed volume form $μ$. An optimal Riemannian metric, for a given volumorphism, is a fixed point of this action in a certain complete metric space containing $\M_μ^s$ as an isometrically embedded subset. We show that a fixed point exists if the orbit of the action is bounded. We also generalize a mean ergodic theorem and a fixed point theorem to the nonlinear setting of complete global Alexandrov nonpositive curvature spaces.

math.DG↗

arXiv2010

Nowhere conformally homogeneous manifolds and limiting Carleman weights

In this note we prove that a generic Riemannian manifold of dimension $\geq 3$ does not admit any nontrivial local conformal diffeomorphisms. This is a conformal analog of a result of Sunada concerning local isometries, and makes precise the principle that generic manifolds in high dimensions do not have conformal symmetries. Consequently, generic manifolds of dimension $\geq 3$ do not admit nontrivial conformal Killing vector fields near any point. As an application to the inverse problem of Calderón on manifolds, this implies that generic manifolds of dimension $\geq 3$ do not admit limiting Carleman weights near any point.

math.DG↗