English

Constructing maximal cofinitary groups

Logic 2024-12-05 v2

Abstract

Improving and clarifying a construction of Horowitz and Shelah, we show how to construct (in ZF\textsf{ZF}, that is, without using the Axiom of Choice) maximal cofinitary groups. Among the groups we construct, one is definable by a formula in second order arithmetic with only a few natural number quantifiers.

Keywords

Cite

@article{arxiv.2105.11318,
  title  = {Constructing maximal cofinitary groups},
  author = {David Schrittesser},
  journal= {arXiv preprint arXiv:2105.11318},
  year   = {2024}
}

Comments

Fixed a gap in the proof. 30 pages

R2 v1 2026-06-24T02:24:33.183Z