Left-separating order types
A well ordering ≺ of a topological space X is left-separating if {x′∈X:x′≺x} is closed in X for any x∈X. A space is left-separated if it has a left-separating well-ordering. The left-separating typeordℓ(X) of a left-separated space X is the minimum of the order types of the left-separating well-orde...
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Veröffentlicht in: | Topology and its applications 2020-09, Vol.283, p.107338, Article 107338 |
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Hauptverfasser: | , |
Format: | Artikel |
Sprache: | eng |
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Zusammenfassung: | A well ordering ≺ of a topological space X is left-separating if {x′∈X:x′≺x} is closed in X for any x∈X. A space is left-separated if it has a left-separating well-ordering. The left-separating typeordℓ(X) of a left-separated space X is the minimum of the order types of the left-separating well-orderings of X.
We prove that(1)if κ is a regular cardinal, then for each ordinal αω, then for each ordinal α |
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ISSN: | 0166-8641 1879-3207 |
DOI: | 10.1016/j.topol.2020.107338 |