Countable tightness is not discretely reflexive in $σ$-compact spaces
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arXiv
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| Hauptverfasser: | , |
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| Format: | Preprint |
| Veröffentlicht: |
2024
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| _version_ | 1866913573551210496 |
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| author | Juhász, István van Mill, Jan |
| author_facet | Juhász, István van Mill, Jan |
| contents | Answering a question raised by V. V. Tkachuk, we present several examples of $σ$-compact spaces, some only consistent and some in ZFC, that are not countably tight but in which the closure of any discrete subset is countably tight. In fact, in some of our examples the closures of all discrete subsets are even first countable. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2411_04523 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Countable tightness is not discretely reflexive in $σ$-compact spaces Juhász, István van Mill, Jan General Topology 54A25, 54A35, 54D45 Answering a question raised by V. V. Tkachuk, we present several examples of $σ$-compact spaces, some only consistent and some in ZFC, that are not countably tight but in which the closure of any discrete subset is countably tight. In fact, in some of our examples the closures of all discrete subsets are even first countable. |
| title | Countable tightness is not discretely reflexive in $σ$-compact spaces |
| topic | General Topology 54A25, 54A35, 54D45 |
| url | https://arxiv.org/abs/2411.04523 |