English

First-order aspects of Artin groups

Logic 2025-07-30 v1

Abstract

We prove several results on the model theory of Artin groups, focusing on Artin groups which are ``far from right-angled Artin groups''. The first result is that if C\mathcal{C} is a class of Artin groups whose irreducible components are acylindrically hyperbolic and torsion-free, then the model theory of Artin groups of type C\mathcal{C} reduces to the model theory of its irreducible components. The second result is that the problem of superstability of a given non-abelian Artin group AA reduces to certain dihedral parabolic subgroups of AA being nn-pure in AA, for certain large enough primes nNn \in \mathbb{N}. The third result is that two spherical Artin groups are elementary equivalent if and only if they are isomorphic. Finally, we prove that the affine Artin groups of type A~n\tilde{A}_n, for n4n \geq 4, can be distinguished from the other simply laced affine Artin groups using existential sentences; this uses homology results of independent interest relying on the recent proof of the K(π,1)K(\pi, 1) conjecture for affine Artin groups.

Keywords

Cite

@article{arxiv.2507.21575,
  title  = {First-order aspects of Artin groups},
  author = {Alberto Cassella and Gianluca Paolini and Giovanni Paolini},
  journal= {arXiv preprint arXiv:2507.21575},
  year   = {2025}
}
R2 v1 2026-07-01T04:23:34.260Z