Countable tightness is compared to the stronger notion of countable fan-tight\-ness. In particular, we prove that countable tightness is equivalent to countable fan-tightness in countably compact regular spaces, and that countable fan-tightness is preserved by pseudo-open compact mappings. We also discuss the behaviour of countable tightness and of countable fan-tightness under the product operation.
@article{118863,
author = {Aleksander V. Arhangel'skii and Angelo Bella},
title = {Countable fan-tightness versus countable tightness},
journal = {Commentationes Mathematicae Universitatis Carolinae},
volume = {37},
year = {1996},
pages = {565-576},
zbl = {0881.54005},
mrnumber = {1426921},
language = {en},
url = {http://dml.mathdoc.fr/item/118863}
}
Arhangel'skii, Aleksander V.; Bella, Angelo. Countable fan-tightness versus countable tightness. Commentationes Mathematicae Universitatis Carolinae, Tome 37 (1996) pp. 565-576. http://gdmltest.u-ga.fr/item/118863/
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