Ordinal remainders of classical ψ-spaces

Alan Dow ; Jerry E. Vaughan

Fundamenta Mathematicae, Tome 219 (2012), p. 83-93 / Harvested from The Polish Digital Mathematics Library

Résumé

Let ω denote the set of natural numbers. We prove: for every mod-finite ascending chain ${T_{α}: α < λ}$ of infinite subsets of ω, there exists $ℳ ⊂ [ω]^{ω}$, an infinite maximal almost disjoint family (MADF) of infinite subsets of the natural numbers, such that the Stone-Čech remainder βψ∖ψ of the associated ψ-space, ψ = ψ(ω,ℳ ), is homeomorphic to λ + 1 with the order topology. We also prove that for every λ < ⁺, where is the tower number, there exists a mod-finite ascending chain ${T_{α}: α < λ}$, hence a ψ-space with Stone-Čech remainder homeomorphic to λ +1. This generalizes a result credited to S. Mrówka by J. Terasawa which states that there is a MADF ℳ such that βψ∖ψ is homeomorphic to ω₁ + 1.

Détail

Publié le : 2012-01-01

Zbl 1251.54027

EUDML-ID : urn:eudml:doc:283311