Countable fan-tightness versus countable tightness
Aleksander V. Arhangel'skii, Angelo Bella · Czech digital mathematics library · 1996
summary: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.