Faculty Publications

Uniformization And Anti-Uniformization Properties Of Ladder Systems

Document Type

Article

Keywords

Countably paracompact, Ladder systems, Normal, Screenable, Uniformizable

Journal/Book/Conference Title

Fundamenta Mathematicae

Volume

181

Issue

3

First Page

189

Last Page

213

Abstract

Natural weakenings of uniformizability of a ladder system on ω1 are considered. It is shown that even assuming CH all the properties may be distinct in a strong sense. In addition, these properties are studied in conjunction with other properties inconsistent with full uniformizability, which we call anti-uniformization properties. The most important conjunction considered is the uniformization property we call countable metacompactness and the anti-uniformization property we call thinness. The existence of a thin, countably metacompact ladder system is used to construct interesting topological spaces: a countably paracompact and nonnormal subspace of ω21 and a countably paracompact, locally compact screenable space which is not paracompact. Whether the existence of a thin, countably metacompact ladder system is consistent is left open. Finally, the relation between the properties introduced and other well known properties of ladder systems, such as Clubsuit sign, is considered.

Department

Department of Mathematics

Original Publication Date

1-1-2004

DOI of published version

10.4064/fm181-3-1

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