English

Template iterations and maximal cofinitary groups

Logic 2013-10-14 v1

Abstract

The main result of the present paper is that ag\mathfrak a_g, the minimal size of maximal cofinitary group, can be of countable cofinality. To prove this we define a natural poset for adding a maximal cofinitary group of a given cardinality, which enjoys certain combinatorial properties allowing it to be used within a similar template forcing construction. Additionally we obtain that ap\mathfrak a_p, the minimal size of a maximal family of almost disjoint permutations, and ae\mathfrak a_e, the minimal size of a maximal eventually different family, can be of countable cofinality.

Keywords

Cite

@article{arxiv.1310.3245,
  title  = {Template iterations and maximal cofinitary groups},
  author = {Vera Fischer and Asger Törnquist},
  journal= {arXiv preprint arXiv:1310.3245},
  year   = {2013}
}

Comments

24 pages

R2 v1 2026-06-22T01:45:20.116Z