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Matroids and isomorphism problems for Bestvina-Brady groups
Abstract
We propose a factorization of the graph isomorphism problem for Bestvina-Brady groups (BBGs) through matroid theory. In particular, we show that finitely presented BBGs depend on their defining graphs only through their cycle matroids. On the other hand, we construct graphs of arbitrarily high connectivity such that they have non-isomorphic cycle matroids but their BBGs are isomorphic. To do so, we prove that if a graph admits a tree clique-spanner, then the Dicks-Leary presentation of its BBG can be explicitly simplified to a right-angled Artin group presentation. In particular, we show that BBGs defined by dually chordal graphs are right-angled Artin groups.
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BibTeX
@misc{chang2026matroids,
title = {{Matroids and isomorphism problems for Bestvina-Brady groups}},
author = {Yu-Chan Chang and Lorenzo Ruffoni},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.16345},
eprint = {2609.16345},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.16345},
}
RIS
TY - UNPB
TI - Matroids and isomorphism problems for Bestvina-Brady groups
AU - Yu-Chan Chang
AU - Lorenzo Ruffoni
PY - 2026
DA - 2026/09/14
PB - arXiv
DO - 10.48550/arxiv.2609.16345
UR - https://arxiv.org/abs/2609.16345
AB - We propose a factorization of the graph isomorphism problem for Bestvina-Brady groups (BBGs) through matroid theory. In particular, we show that finitely presented BBGs depend on their defining graphs only through their cycle matroids. On the other hand, we construct graphs of arbitrarily high connectivity such that they have non-isomorphic cycle matroids but their BBGs are isomorphic. To do so, we prove that if a graph admits a tree clique-spanner, then the Dicks-Leary presentation of its BBG can be explicitly simplified to a right-angled Artin group presentation. In particular, we show that BBGs defined by dually chordal graphs are right-angled Artin groups.
ER -