On cardinal invariants related to Rosenthal families and large-scale topology
Abstract
Given a function f ∈ ωω, a set A ∈ [ω]ω is free for f if f[A] A is finite. For a class of functions ⊂eq ωω, we define ros as the smallest size of a family A⊂eq [ω]ω such that for every f∈ there is a set A ∈ A which is free for f, and as the smallest size of a family F⊂eq such that for every A∈[ω]ω there is f∈F such that A is not free for f. We compare several versions of these cardinal invariants with some of the classical cardinal characteristics of the continuum. Using these notions, we partially answer some questions from arXiv:1911.01336 [math.LO] and arXiv:2004.01979 [math.GN].
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.