Triangulated spheres with holes in triangulated surfaces

Abstract

Let ${\mathbb{S}}_h$ denote a sphere with $h$ holes. Given a triangulation $G$ of a surface $\mathbb{M}$, we consider the question of when $G$ contains a spanning subgraph $H$ such that $H$ is a triangulated ${\mathbb{S}}_h$. We give a new short proof of a theorem of Nevo and Tarabykin that every triangulation $G$ of the torus contains a spanning subgraph which is a triangulated cylinder. For arbitrary surfaces, we prove that every high facewidth triangulation of a surface with $h$ handles contains a spanning subgraph which is a triangulated ${\mathbb{S}}_{2h}$. We also prove that for every $0\le g^{\prime }<g$ and $w\in \mathbb{N}$, there exists a triangulation of facewidth at least $w$ of a surface of Euler genus $g$ that does not have a spanning subgraph which is a triangulated ${\mathbb{S}}_{g^{\prime }}$. Our results are motivated by, and have applications for, rigidity questions in the plane.

arXiv comment8 pages, 0 figures