Constructing maximal cofinitary groups
arXiv:2105.11318 · doi:10.1017/nmj.2022.46
Abstract
Improving and clarifying a construction of Horowitz and Shelah, we show how to construct (in , 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.
Fixed a gap in the proof. 30 pages