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arXiv · 2508.02582

Topological Full Groups of Irreducible Edge Shifts have Solvable Conjugacy Problem

Matteo Tarocchi
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Abstract

In this paper, we solve the conjugacy problem for Topological Full Groups of Irreducible Edge Shifts, introduced by Matui in 2015 and later recontextualized as groups of almost automorphisms of trees by Lederle in 2020. The techniques we use work in a larger class of groups, that of Piecewise-Canonical Homeomorphisms of Edge Shifts (which are essentially the prefix-exchange transformations), which also includes the Houghton groups and the Thompson-like group $QV$, for example. We use strand diagrams, first developed by Belk and Matucci in 2014 to solve the conjugacy problem in Thompson's groups $F$, $T$ and $V$. In addition to strand diagrams, to solve for so-called type 3 reductions we will employ certain commutative semigroups of loops.

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Matteo Tarocchi. 2025-08-04. Topological Full Groups of Irreducible Edge Shifts have Solvable Conjugacy Problem. https://arxiv.org/abs/2508.02582

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