On the logarithmic coarse structures of Lie groups and hyperbolic spaces

TL;DR

This paper characterizes Lie groups that are almost quasiisometric to hyperbolic spaces using sublinear bilipschitz equivalences, linking algebraic deformations and curvature conditions, and explores coarse geometric structures.

Contribution

It provides a new characterization of Lie groups related to hyperbolic spaces via deformations and curvature, and compares sublinear bilipschitz and coarse equivalences.

Findings

Lie groups with certain coarse structures are characterized by algebraic and curvature conditions.

Every coarse equivalence in the logarithmic coarse structure setting is an $O(\log)$-bilipschitz equivalence.

Conditional proof of Tyson's conjecture on hyperbolic building boundaries based on the four exponentials conjecture.

Abstract

We characterize the Lie groups with finitely many connected components that are $O(u)$-bilipschitz equivalent (almost quasiisometric in the sense that the sublinear function $u$ replaces the additive bounds of quasiisometry) to the real hyperbolic space, or to the complex hyperbolic plane. The characterizations are expressed in terms of deformations of Lie algebras and in terms of pinching of sectional curvature of left-invariant Riemannian metrics in the real case. We also compare sublinear bilipschitz equivalence and coarse equivalence, and prove that every coarse equivalence between the logarithmic coarse structures of geodesic spaces is a $O(\log)$-bilipschitz equivalence. The Lie groups characterized are exactly those whose logarithmic coarse structure is equivalent to that of a real hyperbolic space or the complex hyperbolic plane. Finally we point out that a conjecture made by Tyson about the conformal dimensions of the boundaries of certain hyperbolic buildings holds conditionally to the four exponentials conjecture.