A Mitchell-like order for Ramsey and Ramsey-like cardinals
Abstract
Smallish large cardinals are often characterized by the existence of a collection of filters on , each of which is an ultrafilter on the subsets of of some transitive -model of size . We introduce a Mitchell-like order for Ramsey and Ramsey-like cardinals, ordering such collections of small filters. We show that the Mitchell-like order and the resulting notion of rank have all the desirable properties of the Mitchell order on normal measures on a measurable cardinal. The Mitchell-like order behaves robustly with respect to forcing constructions. We show that extensions with cover and approximation properties cannot increase the rank of a Ramsey or Ramsey-like cardinal. We use the results about extensions with cover and approximation properties together with recently developed techniques about soft killing of large-cardinal degrees by forcing to softly kill the ranks of Ramsey and Ramsey-like cardinals.
Keywords
Cite
@article{arxiv.1609.07645,
title = {A Mitchell-like order for Ramsey and Ramsey-like cardinals},
author = {Erin Carmody and Victoria Gitman and Miha E. Habič},
journal= {arXiv preprint arXiv:1609.07645},
year = {2021}
}
Comments
23 pages