Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
5777988 | Topology and its Applications | 2017 | 14 Pages |
Abstract
We study spaces that are continuous images of the usual space [0,Ï1) of countable ordinals. We begin by showing that if Y is such a space and is T3 then Y has a monotonically normal compactification, and is monotonically normal, locally compact and scattered. Examples show that regularity is needed in these results. We investigate when a regular continuous image of the countable ordinals must be compact, paracompact, and metrizable. For example we show that metrizability of such a Y is equivalent to each of the following: Y has a Gδ-diagonal, Y is perfect, Y has a point-countable base, Y has a small diagonal in the sense of HuÅ¡ek, and Y has a Ï-minimal base. Along the way we obtain an absolute version of the Juhasz-Szentmiklossy theorem for small spaces, proving that if Y is any compact Hausdorff space having |Y|â¤âµ1 and having a small diagonal, then Y is metrizable, and we deduce a recent result of Gruenhage from work of Mrowka, Rajagopalan, and Soundararajan.
Keywords
Related Topics
Physical Sciences and Engineering
Mathematics
Geometry and Topology
Authors
Harold Bennett, Sheldon Davis, David Lutzer,