BASICALLY DISCONNECTED SPACES AND PROJECTIVE OBJECTS
BASICALLY DISCONNECTED SPACES ANDPROJECTIVE OBJECTS
한국수학교육학회지시리즈B:순수및응용수학 / Journal of the Korean Society of Mathematical Education Series B: Theoretical Mathematics and Pedagogical Mathematics, (P)3059-0604; (E)3059-1309
2002, v.9 no.1, pp.9-17
Kim, Chang-Il
(Department of Mathematics Education, Dankook University)
Kim, Chang-Il.
(2002). BASICALLY DISCONNECTED SPACES AND PROJECTIVE OBJECTS, 9(1), 9-17.
Abstract
In this Paper, we will show that every basically disconnected space is a projective object in the category $Tych_{\sigma}$ of Tychonoff spaces and $_{\sigma}Z^{#}$ -irreducible maps and that if X is a space such that ${\Beta} {\Lambda} X={\Lambda} {\Beta} X$, then X has a projective cover in $Tych_{\sigma}$. Moreover, observing that for any weakly Linde1of space, ${\Lambda} X : {\Lambda} X\;{\longrightarrow}\;X$ is $_{\sigma}Z^{#}$-irreducible, we will show that the projective objects in $wLind_{\sigma}$/ of weakly Lindelof spaces and $_{\sigma}Z^{#}$-irreducible maps are precisely the basically disconnected spaces.
- keywords
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Weakly <tex> $Lindel{\"{o}}f$</tex> space,
<tex> $_{\sigma}Z^{#}$</tex>-irreducible map,
basically disconnected space