A local treatment of finite alignment and path groupoids of nonfinitely aligned higher-rank graphs

Fuente: arXiv
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Autor principal: Jones, Malcolm
Formato: Preprint
Publicado: 2025
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author Jones, Malcolm
author_facet Jones, Malcolm
contents We give a local treatment of finite alignment by identifying the finitely aligned part of any (not necessarily finitely aligned) higher-rank graph. We show the finitely aligned part is itself a constellation and forms a finitely aligned relative category of paths together with the original higher-rank graph. We show that the elements of the finitely aligned part are precisely those whose cylinder sets are compact, which allows us to give novel definitions of locally compact path and boundary-path spaces for nonfinitely aligned higher-rank graphs. We extend a semigroup action and the associated semidirect product groupoid developed by Renault and Williams to define ample Hausdorff path and boundary-path groupoids. The groupoids are amenable for nonfinitely aligned k-graphs by a result of Renault and Williams. In the finitely aligned case, the path groupoids coincide with Spielberg's groupoids, and the boundary-path groupoid has an inverse semigroup model via a result of Ortega and Pardo.
format Preprint
id arxiv_https___arxiv_org_abs_2503_21031
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle A local treatment of finite alignment and path groupoids of nonfinitely aligned higher-rank graphs
Jones, Malcolm
Rings and Algebras
Category Theory
Operator Algebras
18A32, 22A22, 16W22, 46L05
We give a local treatment of finite alignment by identifying the finitely aligned part of any (not necessarily finitely aligned) higher-rank graph. We show the finitely aligned part is itself a constellation and forms a finitely aligned relative category of paths together with the original higher-rank graph. We show that the elements of the finitely aligned part are precisely those whose cylinder sets are compact, which allows us to give novel definitions of locally compact path and boundary-path spaces for nonfinitely aligned higher-rank graphs. We extend a semigroup action and the associated semidirect product groupoid developed by Renault and Williams to define ample Hausdorff path and boundary-path groupoids. The groupoids are amenable for nonfinitely aligned k-graphs by a result of Renault and Williams. In the finitely aligned case, the path groupoids coincide with Spielberg's groupoids, and the boundary-path groupoid has an inverse semigroup model via a result of Ortega and Pardo.
title A local treatment of finite alignment and path groupoids of nonfinitely aligned higher-rank graphs
topic Rings and Algebras
Category Theory
Operator Algebras
18A32, 22A22, 16W22, 46L05
url https://arxiv.org/abs/2503.21031