English

Line Patterns in Free Groups

Group Theory 2014-11-11 v4

Abstract

We study line patterns in a free group by considering the topology of the decomposition space, a quotient of the boundary at infinity of the free group related to the line pattern. We show that the group of quasi-isometries preserving a line pattern in a free group acts by isometries on a related space if and only if there are no cut pairs in the decomposition space.

Keywords

Cite

@article{arxiv.1006.2123,
  title  = {Line Patterns in Free Groups},
  author = {Christopher H. Cashen and Natasa Macura},
  journal= {arXiv preprint arXiv:1006.2123},
  year   = {2014}
}

Comments

35 pages, 22 figures, PDFLatex; v2. finite index requires extra hypothesis; v3. 37 pages, 24 figures: updated references and add example in Section 6.3 of a rigid pattern for which the free group is not finite index in the group of pattern preserving quasi-isometries; v4. 40 pages, 26 figures: improved exposition and add example in Section 6.4 of a rigid pattern whose cube complex is not a tree

R2 v1 2026-06-21T15:34:37.966Z