English

Definable sets in a hyperbolic group

Group Theory 2013-05-07 v5

Abstract

We give a description of definable sets P=(p1,...,pm)P=(p_1,..., p_m) in a free non-abelian group FF and in a torsion-free non-elementary hyperbolic group GG that follows from our work on the Tarski problems. This answers Malcev's question for FF. As a corollary we show that proper non-cyclic subgroups of FF and GG are not definable and prove Bestvina and Feighn's result that definable subsets P=(p)P=(p) in a free group are either negligible or co-negligible in their terminology.

Keywords

Cite

@article{arxiv.1111.0577,
  title  = {Definable sets in a hyperbolic group},
  author = {Olga Kharlampovich and Alexei Myasnikov},
  journal= {arXiv preprint arXiv:1111.0577},
  year   = {2013}
}

Comments

Corollary of Theorem 3 was corrected and incorporated into Theorem 3

R2 v1 2026-06-21T19:29:51.601Z