English

Selective independence

Logic 2019-12-24 v1

Abstract

Let i\mathfrak{i} denote the minimal cardinality of a maximal independent family and let aT\mathfrak{a}_T denote the minimal cardinality of a maximal family of pairwise almost disjoint subtrees of 2<ω2^{<\omega}. Using a countable support iteration of proper, ωω^\omega\omega-bounding posets of length ω2\omega_2 over a model of CH, we show that consistently i<aT\mathfrak{i}<\mathfrak{a}_T. Moreover, we show that the inequality can be witnessed by a co-analytic maximal independent family of size 1\aleph_1 in the presence of a Δ31\Delta^1_3 definable well-order of the reals. The main result of the paper can be viewed as a partial answer towards the well-known open problem of the consistency of i<a\mathfrak{i}<\mathfrak{a}.

Keywords

Cite

@article{arxiv.1912.10332,
  title  = {Selective independence},
  author = {Vera Fischer},
  journal= {arXiv preprint arXiv:1912.10332},
  year   = {2019}
}

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8 pages