On finite index reflection subgroups of discrete reflection groups

Abstract

Let $G$ be a discrete group generated by reflections in hyperbolic or Euclidean space, and $H\subset G$ be a finite index subgroup generated by reflections. Suppose that the fundamental chamber of $G$ is a finite volume polytope with $k$ facets. In this paper, we prove that the fundamental chamber of $H$ has at least $k$ facets.

5 pages

Cited by in corpus (4)

• On hyperbolic Coxeter polytopes with mutually intersecting facets
• Reflection subgroups of Coxeter groups
• Essential hyperbolic Coxeter polytopes
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