English

The Cofinal Strong Chang Conjecture from Models of Determinacy

Logic 2026-05-28 v1

Abstract

In chapter 9 of his book "The Axiom of Determinacy, Forcing Axioms, and the Nonstationary Ideal", Woodin shows how to force the Strong Chang Conjecture over models of determinacy using Pmax\mathbb{P}_{\mathrm{max}}. We show here how a modification of the proof implies that such extensions actually verify the stronger cofinal version of the conjecture. This stronger version has important consequences on the semi-properness of small forcing, allowing us to prove the consistency of the theory "ZFC + Namba forcing is semiproper + ΘUB=ω3\Theta^{UB}=\omega_3". We then use the constructions of this proof to also show that Woodin ()UB(\ast)_{UB} axiom implies the conjecture.

Keywords

Cite

@article{arxiv.2605.28492,
  title  = {The Cofinal Strong Chang Conjecture from Models of Determinacy},
  author = {Corentin Lagadec},
  journal= {arXiv preprint arXiv:2605.28492},
  year   = {2026}
}

Comments

17 pages