On the strength of the finite intersection principle
Abstract
We study the logical content of several maximality principles related to the finite intersection principle () 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 over , while others are strictly weaker, and incomparable with . We show that there is a computable instance of 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 implying the omitting partial types principle (). We also show that, modulo induction, lies strictly below the atomic model theorem ().
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