Coarse $\mathcal{Z}$-Boundaries for Groups

Craig R. Guilbault; Molly A. Moran

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arXiv · 2010.08064

Coarse $\mathcal{Z}$-Boundaries for Groups

Craig R. Guilbault·Molly A. Moran

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Abstract

We generalize Bestvina's notion of a $\mathcal{Z}$-boundary for a group to that of a "coarse $\mathcal{Z}$-boundary." We show that established theorems about $\mathcal{Z}$-boundaries carry over nicely to the more general theory, and that some wished-for properties of $\mathcal{Z}$-boundaries become theorems when applied to coarse $\mathcal{Z}$-boundaries. Most notably, the property of admitting a coarse $\mathcal{Z}$-boundary is a pure quasi-isometry invariant. In the process, we streamline both new and existing definitions by introducing the notion of a "model $\mathcal{Z}$-geometry." In accordance with the existing theory, we also develop an equivariant version of the above -- that of a "coarse $E\mathcal{Z}$-boundary."

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BibTeX RIS

Craig R. Guilbault, Molly A. Moran. 2020-10-15. Coarse $\mathcal{Z}$-Boundaries for Groups. https://arxiv.org/abs/2010.08064

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