English

Automorphism groups of finite topological rank

Group Theory 2019-08-26 v5 Logic

Abstract

We offer a criterion for showing that the automorphism group of an ultrahomogeneous structure is topologically 2-generated and even has a cyclically dense conjugacy class. We then show how finite topological rank of the automorphism group of an ω\omega-categorical structure can go down to reducts. Together, those results prove that a large number of ω\omega-categorical structures that appear in the literature have an automorphism group of finite topological rank. In fact, we are not aware of any ω\omega-categorical structure to which they do not apply (assuming the automorphism group has no compact quotients). We end with a few questions and conjectures.

Keywords

Cite

@article{arxiv.1709.01918,
  title  = {Automorphism groups of finite topological rank},
  author = {Itay Kaplan and Pierre Simon},
  journal= {arXiv preprint arXiv:1709.01918},
  year   = {2019}
}