Cartan inverse semigroups and twisted Steinberg algebras
Abstract
We introduce the notion of a Cartan inverse semigroup and an (algebraic) semi-Cartan subalgebra in an R-algebra A, providing a purely algebraic analogue of Cartan semigroups and semi-Cartan subalgebras in a C*-algebra. This extends the theory of quasi-Cartan subalgebras, shifting the focus from designated subalgebras to designated subsemigroups. Our main result characterises twisted Steinberg algebras in terms of the existence of a Cartan inverse semigroup: we show that an R-algebra admits a Cartan inverse semigroup if and only if it is isomorphic to a twisted Steinberg algebra. Moreover, when our construction is applied to a twisted Steinberg algebra over an ample Hausdorff groupoid, the constructed twist is naturally isomorphic to the original one.
Related
- Zhang twists for semigroups and groupoids, with applications to Steinberg algebras
- Covariant representations of actions of inverse semigroups: a new approach to the reduced and essential crossed-product C*-algebras
- Discretisation in algebraic K-theory of independent ample groupoids and their Steinberg algebras
- Baer-Type Ring Characterizations of Steinberg Algebras, with Applications to Leavitt Path Algebras
- The Cartan determinant conjecture for representation-finite Artin algebras
BibTeX
@misc{brownlowe2026cartan,
title = {{Cartan inverse semigroups and twisted Steinberg algebras}},
author = {Nathan Brownlowe and Lisa Orloff Clark and Ying-Fen Lin and Lynnel D. Naingue},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.04548},
eprint = {2610.04548},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.04548},
}
RIS
TY - UNPB
TI - Cartan inverse semigroups and twisted Steinberg algebras
AU - Nathan Brownlowe
AU - Lisa Orloff Clark
AU - Ying-Fen Lin
AU - Lynnel D. Naingue
PY - 2026
DA - 2026/10/03
PB - arXiv
DO - 10.48550/arxiv.2610.04548
UR - https://arxiv.org/abs/2610.04548
AB - We introduce the notion of a Cartan inverse semigroup and an (algebraic) semi-Cartan subalgebra in an R-algebra A, providing a purely algebraic analogue of Cartan semigroups and semi-Cartan subalgebras in a C*-algebra. This extends the theory of quasi-Cartan subalgebras, shifting the focus from designated subalgebras to designated subsemigroups. Our main result characterises twisted Steinberg algebras in terms of the existence of a Cartan inverse semigroup: we show that an R-algebra admits a Cartan inverse semigroup if and only if it is isomorphic to a twisted Steinberg algebra. Moreover, when our construction is applied to a twisted Steinberg algebra over an ample Hausdorff groupoid, the constructed twist is naturally isomorphic to the original one.
ER -