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Monotone versions of some selection principles - MaRDI portal

Monotone versions of some selection principles (Q1738936)

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scientific article; zbMATH DE number 7047516
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English
Monotone versions of some selection principles
scientific article; zbMATH DE number 7047516

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    Monotone versions of some selection principles (English)
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    24 April 2019
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    Space $X$ is \textsf{ SS-mM} if there is an operator assigning to every sequence $\mathcal U=\langle \mathcal U_n\rangle$ of open covers of $X$ a sequence $r(\mathcal U)=\langle r(\mathcal U)_n\rangle$ so that $\cup_nr(\mathcal U)_n$ is an open cover of $X$, $r(\mathcal U)_n$ refines $\mathcal U_n$ for every $n$ and for any two sequences $\mathcal U=\langle \mathcal U_n\rangle$ and $\mathcal V=\langle \mathcal V_n\rangle$ of open covers if $\mathcal U_n$ refines $\mathcal V_n$ for each $n$ then $r(\mathcal U)_n$ refines $r(\mathcal V)_n$ for each $n$. \textsf{ W} versions (replacing one or both \textsf{ S}) weaken refinement for individual members of the sequences to refinement for the union of members of the sequences. \textsf{ R} and \textsf{ H} (replacing \textsf{ M}) versions relate to the Hurewicz and Rothberger properties. Connections amongst these properties, as well as monotone Lindelöfness, are considered. It is also observed that the \textsf{ WS} versions are uninteresting and the \textsf{ WW} slightly less so. Local versions are also considered.
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    Monotonically Lindelöf space
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    \textsf{ SS-mM} space
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    \textsf{ SS-mR} space
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    \textsf{ SS-mH} space
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    \textsf{ SW-mM} space
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    \textsf{ SW-mR} space
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    \textsf{ SW-mH} space
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    \textsf{ WW-mM} space
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    \textsf{ WW-mR} space
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    \textsf{ WW-mH} space
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    \textsf{ WS-mM} space
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    \textsf{ WS-mR} space
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    \textsf{ WS-mH} space
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