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Boundary Value Problem and Discrete Schwarz-Pick Lemma for Generalized Hyperbolic Circle Packings

Guangming Hu, Ziping Lei, Yanlin Li, Hao Yu

Abstract

In 1991, Beardon and Stephenson [2] generalized the classical Schwarz-Pick lemma in hyperbolic geometry to the discrete Schwarz-Pick lemma for Andreev circle packings. This paper continues to investigate the discrete Schwarz-Pick lemma for generalized circle packings (including circle, horocycle or hypercycle) in hyperbolic background geometry. Since the discrete Schwarz-Pick lemma is to compare some geometric quantities of two generalized circle packings with different boundary values, we first show the existence and rigidity of generalized circle packings with boundary values, and then we introduce the method of combinatorial Calabi flows to find the generalized circle packings with boundary values. Moreover, motivated by the method of He [21], we propose the maximum principle for generalized circle packings. Finally, we use the maximum principle to prove the discrete Schwarz-Pick lemma for generalized circle packings.

Boundary Value Problem and Discrete Schwarz-Pick Lemma for Generalized Hyperbolic Circle Packings

Abstract

In 1991, Beardon and Stephenson [2] generalized the classical Schwarz-Pick lemma in hyperbolic geometry to the discrete Schwarz-Pick lemma for Andreev circle packings. This paper continues to investigate the discrete Schwarz-Pick lemma for generalized circle packings (including circle, horocycle or hypercycle) in hyperbolic background geometry. Since the discrete Schwarz-Pick lemma is to compare some geometric quantities of two generalized circle packings with different boundary values, we first show the existence and rigidity of generalized circle packings with boundary values, and then we introduce the method of combinatorial Calabi flows to find the generalized circle packings with boundary values. Moreover, motivated by the method of He [21], we propose the maximum principle for generalized circle packings. Finally, we use the maximum principle to prove the discrete Schwarz-Pick lemma for generalized circle packings.

Paper Structure

This paper contains 10 sections, 15 theorems, 125 equations, 12 figures, 1 table.

Key Result

Theorem 1.1

Given a closed topological surface $S_{g,n}$ with a triangulation $\mathcal{T} = (V, E, F)$ as in subsection GCPS, for any prescribed geodesic curvatures $\hat{k} \in \mathbb{R}_{>0}^{|V^{\partial}|}$ and prescribed total geodesic curvatures $\hat{T} \in \mathbb{R}^{|V^{\circ}|}_{>0}$, there exists Furthermore, the generalized circle packing $P$, if it exists, is unique up to isometry.

Figures (12)

  • Figure 1: The generalized circles on $\mathbb{H}^2$.
  • Figure 2: The inner angle $\theta$ of the arc $C$ for hypercycle.
  • Figure 3: The generalized circle packing of the triangle $f$.
  • Figure 4: The triangle $f$ and hyperbolic triangle $\hat{f}$.
  • Figure 5: The hyperbolic triangles of $f$.
  • ...and 7 more figures

Theorems & Definitions (31)

  • Theorem 1.1
  • Definition 1.2
  • Theorem 1.3
  • Theorem 1.4
  • Theorem 1.5
  • Theorem 1.6
  • Lemma 2.1
  • Remark 2.2
  • Lemma 3.1
  • proof
  • ...and 21 more