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Concerning \(n\)-mutual aposyndesis in hyperspaces - MaRDI portal

Concerning \(n\)-mutual aposyndesis in hyperspaces (Q2901997)

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scientific article; zbMATH DE number 6062722
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Concerning \(n\)-mutual aposyndesis in hyperspaces
scientific article; zbMATH DE number 6062722

    Statements

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    1 August 2012
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    continuum
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    hyperspace
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    \(n\)-mutual aposyndesis
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    Concerning \(n\)-mutual aposyndesis in hyperspaces (English)
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    For a positive integer \(n\), a continuum (i.e., a nonempty compact connected metric space with more than one point) \(X\) is said to be \(n\)-mutually aposyndetic if for each set \(\{ p_1, p_2 , \dots, p_n\}\) of \(n\) distinct points, there exists a pairwise disjoint family \(\{ M_i : i =1,2,\dots , n\}\) of subcontinua of \(X\) such that \(p_i\) is contained in the interior of \(M_i\) for each \(i\). A continuum is said to be mutually aposyndetic if it is \(2\)-mutually aposyndetic. \textit{H. Hosokawa} [Houston J.\ Math.\ 35, No.\ 1, 131--137 (2009; Zbl 1211.54027)] proved that for each continuum \(X\) and for each \(n \geq 2\), the hyperspace \(C_n(X)\) of all nonempty closed subsets of \(X\) with at most \(n\) components endowed with the Hausdorff metric is mutually aposyndetic. He also asked whether the hyperspace \(2^X\) of all nonempty closed subsets of \(X\) endowed with the Hausdorff metric is mutually aposyndetic. This question was answered by \textit{J. M. Martinez-Montejano} [Quest.\ Answers Gen.\ Topology 28, No. 2, 197--201 (2010; Zbl 1222.54012)] affirmatively. In the paper under review, the author improves Martinez-Montejano's theorem by proving the following: For each continuum \(X\) and each positive integer \(n\), the hyperspace \(2^X\) is \(n\)-mutually aposyndetic.
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