English

Isometry groups of skewed $\Gamma$-complexes

Geometric Topology 2022-02-22 v1 Group Theory

Abstract

Let AΓA_\Gamma be a right-angled Artin group. Charney, Vogtmann and the author constructed an outer space for Out(AΓ)\text{Out}(A_\Gamma) generalizing both CVnCV_n for Out(Fn)\text{Out}(F_n) and the symmetric space SLn(R)/SOn(R)\text{SL}_n(\mathbb{R})/\text{SO}_n(\mathbb{R}) for GLn(Z)\text{GL}_n(\mathbb{Z}). Points in this space are equivalence classes of pairs (X,ρ)(X,\rho) where ρ ⁣:XSΓ\rho\colon X\rightarrow \mathbb{S}_\Gamma is a homotopy equivalence from XX to the Salvetti complex SΓ\mathbb{S}_\Gamma and XX is a locally CAT(0) space called a skewed Γ\Gamma-complex. In this note we show that any isometry of a skewed Γ\Gamma-complex which is homotopic to the identity lies in the identity component of Isom(X)\text{Isom}(X). As a corollary, we prove that the group of path components of Isom(X)\text{Isom}(X) is finite and injects into Out(AΓ)\text{Out}(A_\Gamma).

Keywords

Cite

@article{arxiv.2202.09860,
  title  = {Isometry groups of skewed $\Gamma$-complexes},
  author = {Corey Bregman},
  journal= {arXiv preprint arXiv:2202.09860},
  year   = {2022}
}

Comments

13 pages, no figures. Comments welcome

R2 v1 2026-06-24T09:46:36.980Z