English

Brown's Criterion and classifying spaces for families

Group Theory 2020-04-24 v3 Algebraic Topology

Abstract

Let GG be a group and F\mathcal{F} be a family of subgroups closed under conjugation and subgroups. A model for the classifying space EFGE_{\mathcal{F}} G is a GG-CW-complex XX such that every isotropy group belongs to F\mathcal{F}, and for all HFH\in \mathcal{F} the fixed point subspace XHX^H is contractible. The group GG is of type F-Fn\mathcal{F}\text{-}\mathrm{F}_{n} if it admits a model for EFGE_\mathcal{F} G with nn-skeleton with compact orbit space. The main result of the article provides is a characterization of F-Fn\mathcal{F}\text{-}\mathrm{F}_{n} analogue to Brown's criterion for FPn\mathrm{FP}_n. As applications we provide criteria for this type of finiteness properties with respect to families to be preserved by finite extensions, a result that contrast with examples of Leary and Nucinkis. We also recover L\"uck's characterization of property Fn\underline{\mathrm{F}}_n in terms of the finiteness properties of the Weyl groups.

Keywords

Cite

@article{arxiv.1908.05543,
  title  = {Brown's Criterion and classifying spaces for families},
  author = {Eduardo Martínez-Pedroza and Luis Jorge Sánchez Saldaña},
  journal= {arXiv preprint arXiv:1908.05543},
  year   = {2020}
}

Comments

Version accepted for publication in JPAA

R2 v1 2026-06-23T10:48:15.287Z