Classes of barren extensions
Abstract
Henle, Mathias, and Woodin proved that, provided that holds in a model of ZF, then forcing with over adds no new sets of ordinals, thus earning the name a "barren" extension. Moreover, under an additional assumption, they proved that this generic extension preserves all strong partition cardinals. This forcing thus produces a model , where is a Ramsey ultrafilter, with many properties of the original model . This begged the question of how important the Ramseyness of is for these results. In this paper, we show that several classes of -closed forcings which generate non-Ramsey ultrafilters have the same properties. Such ultrafilters include Milliken-Taylor ultrafilters, a class of rapid p-points of Laflamme, -arrow p-points of Baumgartner and Taylor, and extensions to a class of ultrafilters constructed by Dobrinen, Mijares and Trujillo. Furthermore, the class of Boolean algebras , , forcing non-p-points also produce barren extensions.
Keywords
Cite
@article{arxiv.1911.06936,
title = {Classes of barren extensions},
author = {Natasha Dobrinen and Daniel Hathaway},
journal= {arXiv preprint arXiv:1911.06936},
year = {2023}
}
Comments
Accepted to JSL. A few revisions from the last posting