English

Entropy and finiteness of groups with acylindrical splittings

Metric Geometry 2018-04-13 v2 Differential Geometry Geometric Topology

Abstract

We prove that there exists a positive, explicit function F(k,E)F(k, E) such that, for any group GG admitting a kk-acylindrical splitting and any generating set SS of GG with Ent(G,S)<E\mathrm{Ent}(G,S)<E, we have SF(k,E)|S| \leq F(k, E). We deduce corresponding finiteness results for classes of groups possessing acylindrical splittings and acting geometrically with bounded entropy: for instance, DD-quasiconvex kk-malnormal amalgamated products acting on δ\delta-hyperbolic spaces or on CAT(0)CAT(0)-spaces with entropy bounded by EE. A number of finiteness results for interesting families of Riemannian or metric spaces with bounded entropy and diameter also follow: Riemannian 2-orbifolds, non-geometric 33-manifolds, higher dimensional graph manifolds and cusp-decomposable manifolds, ramified coverings and, more generally, CAT(0)-groups with negatively curved splittings.

Keywords

Cite

@article{arxiv.1711.06210,
  title  = {Entropy and finiteness of groups with acylindrical splittings},
  author = {Filippo Cerocchi and Andrea Sambusetti},
  journal= {arXiv preprint arXiv:1711.06210},
  year   = {2018}
}

Comments

38 pages, 6 figures; added a finiteness result concerning non-geometric 3-manifolds. Comments are welcome!