English

Closed Unbounded classes and the Haertig Quantifier Model

Logic 2019-03-08 v1

Abstract

We show that assuming modest large cardinals, there is a definable class of ordinals, closed and unbounded beneath every uncountable cardinal, so that for any closed and unbounded subclasses P,QP, Q, L[P],,P\langle L[P],\in ,P \rangle and L[Q],,Q\langle L[Q],\in ,Q \rangle possess the same reals, satisfy the Generalised Continuum Hypothesis, and moreover are elementarily equivalent. The theory of such models is thus invariant under set forcing. They also all have a rich structure satisfying many of the usual combinatorial principles and a definable wellorder of the reals. One outcome is that we can characterize the inner model constructed using definability in the language augmented by the H\"artig quantifier when such a PP is itself CardCard.

Keywords

Cite

@article{arxiv.1903.02663,
  title  = {Closed Unbounded classes and the Haertig Quantifier Model},
  author = {Philip Welch},
  journal= {arXiv preprint arXiv:1903.02663},
  year   = {2019}
}
R2 v1 2026-06-23T08:00:32.822Z