English

Harmonic projections in negative curvature II: large convex sets

Differential Geometry 2025-04-22 v3

Abstract

An important result in the theory of harmonic maps is due to Benoist--Hulin: given a quasi-isometry f:XYf:X\to Y between pinched Hadamard manifolds, there exists a unique harmonic map at a finite distance from ff. Here we show existence of harmonic maps under a weaker condition on ff, that we call non-collapsing -- we require that the following two conditions hold uniformly in xXx\in X: (1) average distance from f(x)f(x) to f(y)f(y) for yy on the sphere of radius RR centered at xx grows linearly with RR (2) the pre-image under ff of small cones with apex f(x)f(x) have low harmonic measures on spheres centered at xx. Using these ideas, we also continue the previous work of the author on existence of harmonic maps that are at a finite distance from projections to certain convex sets. We show this existence in a pinched negative curvature setting, when the convex set is large enough. For hyperbolic spaces, this includes the convex hulls of open sets in the sphere at infinity with sufficiently regular boundary.

Keywords

Cite

@article{arxiv.2310.05796,
  title  = {Harmonic projections in negative curvature II: large convex sets},
  author = {Ognjen Tošić},
  journal= {arXiv preprint arXiv:2310.05796},
  year   = {2025}
}

Comments

27 pages, 1 figure