English

Subcomplete forcing principles and definable well-orders

Logic 2018-02-15 v2

Abstract

It is shown that the boldface maximality principle for subcomplete forcing, together with the assumption that the universe has only set-many grounds, implies the existence of a (parameter-free) definable well-ordering of P(ω1)\mathcal{P}(\omega_1). The same conclusion follows from the boldface maximality for subcomplete forcing, assuming there is no inner model with an inaccessible limit of measurable cardinals. Similarly, the bounded subcomplete forcing axiom, together with the assumption that x#x^\# does not exist, for some xω1x\subseteq\omega_1, implies the existence of a well-order of P(ω1)\mathcal{P}(\omega_1) which is Δ1\Delta_1-definable without parameters, and Δ1(Hω2)\Delta_1(H_{\omega_2})-definable using a subset of ω1\omega_1 as a parameter. This well-order is in L(P(ω1))L(\mathcal{P}(\omega_1)). Enhanced version of bounded forcing axioms are introduced that are strong enough to have the implications of the maximality principles mentioned above.

Keywords

Cite

@article{arxiv.1708.08167,
  title  = {Subcomplete forcing principles and definable well-orders},
  author = {Gunter Fuchs},
  journal= {arXiv preprint arXiv:1708.08167},
  year   = {2018}
}

Comments

23 pages, sections on "more reflection" and enhanced bounded forcing axioms added

R2 v1 2026-06-22T21:24:46.327Z