English

On the asymmetry of stars at infinity

Group Theory 2020-01-20 v1 Geometric Topology

Abstract

Given a bordified space, Karlsson defines an incidence geometry of stars at infinity. These stars and their incidence are closely related to well-understood objects when the space is hyperbolic, CAT(0), or a bounded convex domain with the Hilbert metric. A question stemming from Karlsson's original paper was whether or not the relation of one boundary point being included in a star of another boundary point is symmetric. This paper provides an example demonstrating that this relation in the star boundary of the three-tree Diestel-Leader graph DL3(q)DL_3(q) is not symmetric. In doing so, some interesting bounds on distance in Diestel-Leader graphs are utilized.

Keywords

Cite

@article{arxiv.2001.06411,
  title  = {On the asymmetry of stars at infinity},
  author = {Keith Jones and Gregory A. Kelsey},
  journal= {arXiv preprint arXiv:2001.06411},
  year   = {2020}
}

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10 pages