Abstract:Countable tightness is compared to the stronger notion of countable fan-tightness. 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.
Keywords: tightness, fan-tightness, countably compact spaces, pseudo-compact space, P-point, biquotient mapping
AMS Subject Classification: 54A25