English

Spherical convexity and hyperbolic metric

Complex Variables 2017-04-27 v1

Abstract

Let Ω\Omega be a domain in C\mathbb{C} with hyperbolic metric λΩ(z)dz\lambda_\Omega(z)|dz| of Gaussian curvature 4.-4. Mejia and Minda proved in their 1990 paper that Ω\Omega is (Euclidean) convex if and only if d(z,Ω)λΩ(z)1/2d(z,\partial\Omega)\lambda_\Omega(z)\ge1/2 for zΩ,z\in\Omega, where d(z,Ω)d(z,\partial\Omega) denotes the Euclidean distance from zz to the boundary Ω.\partial\Omega. In the present note, we will provide similar characterizations of spherically convex domains in terms of the spherical density of the hyperbolic metric.

Keywords

Cite

@article{arxiv.1704.07944,
  title  = {Spherical convexity and hyperbolic metric},
  author = {Toshiyuki Sugawa},
  journal= {arXiv preprint arXiv:1704.07944},
  year   = {2017}
}

Comments

8 pages

R2 v1 2026-06-22T19:27:58.613Z