Total Failure of Approachability at Successors of Singulars of Countable Cofinality
Abstract
Relative to class many supercompact cardinals, we construct a model of + where for every singular cardinal δ of countable cofinality and every regular uncountable μ<δ there are stationarily many non-approachable points of cofinality μ in δ+. This answers a question of Mitchell and provides a decisive answer to a question of Foreman and Shelah.
0
Turn this paper into a full lesson
ArcXiv compiles a staged curriculum from this paper: 8-12 lessons across beginner → advanced, synthesised section guides, visuals, flashcards, a quiz, exercises, and on-demand deep dives per section. Grounded in the abstract, never invented.