English

Nairian Models

Logic 2025-02-03 v1

Abstract

We introduce a hierarchy of models of the Axiom of Determinacy called \emph{Nairian models}. Forcing over the simplest Nairian model, we obtain a model of ZFC+MM++(c)+¬ω3+¬(ω3){\sf{ZFC}}+{\sf{MM^{++}}}(c)+\neg\square_{\omega_3}+\neg\square(\omega_3). Then, fixing n[3,ω)n\in [3, \omega), we design a Nairian model and force over it to produce a model of ZFC+MM++(c)+i[2,n]¬(ωi){\sf{ZFC}}+{\sf{MM^{++}}}(c)+\forall i\in [2, n]\, \neg\square(\omega_i). We also build a Nairian model that satisfies ZF+"ω1{\sf{ZF}}+"\omega_1 is a supercompact cardinal." We obtain as corollaries of these constructions (1) the consistent failure of the Iterability Conjecture for the Mitchell-Schindler Kc\sf{K}^{c} construction, (2) the consistent failure of the Iterability Conjecture for the Kc\sf{K}^{c} construction using 222ω2^{2^{\dots 2^{\omega}}}-complete (for any finite stack of exponents) background extenders, answering a strong version of a question asked by Steel, and (3) a negative answer to Trang's question whether ZF+"ω1{\sf{ZF}}+"\omega_1 is a supercompact cardinal" is equiconsistent with ZFC+"{\sf{ZFC}}+"there is a proper class of Woodin cardinals that are limits of Woodin cardinals." These corollaries identify obstructions to extending the methods of (descriptive) inner model theory past a Woodin cardinal which is a limit of Woodin cardinals.

Keywords

Cite

@article{arxiv.2501.18958,
  title  = {Nairian Models},
  author = {Douglas Blue and Paul B. Larson and Grigor Sargsyan},
  journal= {arXiv preprint arXiv:2501.18958},
  year   = {2025}
}
R2 v1 2026-06-28T21:27:09.645Z