Geodesic
Countable fan-tightness versus countable tightness
Commentationes Mathematicae Universitatis Carolinae, Tome 37 (1996) no. 3, pp. 565-576 Cet article a éte moissonné depuis la source Czech Digital Mathematics Library

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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.
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.
Classification : 54A20, 54A25, 54C10, 54D30
Keywords: tightness; fan-tightness; countably compact spaces; pseudo-compact space; P-point; biquotient mapping 
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Arhangel'skii, A. V.; Bella, A. Countable fan-tightness versus countable tightness. Commentationes Mathematicae Universitatis Carolinae, Tome 37 (1996) no. 3, pp. 565-576. http://geodesic.mathdoc.fr/item/CMUC_1996_37_3_a13/