Hyperbolic models for CAT(0) spaces
Abstract
We introduce two new tools for studying CAT(0) spaces: \emph{curtains}, versions of cubical hyperplanes; and the \emph{curtain model}, a counterpart of the curve graph. These tools shed new light on CAT(0) spaces, allowing us to prove a dichotomy of a rank-rigidity flavour, establish Ivanov-style rigidity theorems for isometries of the curtain model, find isometry-invariant copies of its Gromov boundary in the visual boundary of the underlying CAT(0) space, and characterise rank-one isometries both in terms of their action on the curtain model and in terms of curtains. Finally, we show that the curtain model is universal for WPD actions over all groups acting properly on the CAT(0) space.
Cite
@article{arxiv.2207.14127,
title = {Hyperbolic models for CAT(0) spaces},
author = {Harry Petyt and Davide Spriano and Abdul Zalloum},
journal= {arXiv preprint arXiv:2207.14127},
year = {2024}
}
Comments
54 pages. v4: Accepted version. v3: Small corrections and clarifications, added an extra figure. v2: Added Section 9, unifying the family of models from v1 into a single space