English

On the strength of the finite intersection principle

Logic 2014-12-15 v1

Abstract

We study the logical content of several maximality principles related to the finite intersection principle (F\IPF\IP) in set theory. Classically, these are all equivalent to the axiom of choice, but in the context of reverse mathematics their strengths vary: some are equivalent to \ACA\ACA over \RCA\RCA, while others are strictly weaker, and incomparable with \WKL\WKL. We show that there is a computable instance of F\IPF\IP all of whose solutions have hyperimmune degree, and that every computable instance has a solution in every nonzero c.e.\ degree. In terms of other weak principles previously studied in the literature, the former result translates to F\IPF\IP implying the omitting partial types principle (OPT\mathsf{OPT}). We also show that, modulo Σ20\Sigma^0_2 induction, F\IPF\IP lies strictly below the atomic model theorem (AMT\mathsf{AMT}).

Keywords

Cite

@article{arxiv.1109.3374,
  title  = {On the strength of the finite intersection principle},
  author = {Damir D. Dzhafarov and Carl Mummert},
  journal= {arXiv preprint arXiv:1109.3374},
  year   = {2014}
}

Comments

This paper corresponds to section 3 of arXiv:1009.3242, "Reverse mathematics and equivalents of the axiom of choice", which has been abbreviated and divided into two pieces for publication