The countable spaces whose product with the sequential fan S, have countable tightness are characterized. As a consequence. it is shown that if ?l x S, has countable tightness then X has countable fan-tightness.
Around tight points
β Scribed by A. Bella; V.I. Malykhin
- Book ID
- 104295289
- Publisher
- Elsevier Science
- Year
- 1998
- Tongue
- English
- Weight
- 557 KB
- Volume
- 87
- Category
- Article
- ISSN
- 0166-8641
No coin nor oath required. For personal study only.
β¦ Synopsis
We present three examples of countable spaces with a single nonisolated point. The first gives, assuming CH, a FrCchet-Urysohn tight point which does not have countable absolute tightness; the second, constructed with the help of o, gives a tight non-weakly Frkchet-Urysohn point without countable absolute tightness; the third gives a weakly Frbchet-Urysohn point which is not Frechet-Urysohn, has countable fan-tightness but is not tight.
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