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JOURNALS // Vestnik Moskovskogo Universiteta. Seriya 1. Matematika. Mekhanika // Archive

Vestnik Moskov. Univ. Ser. 1. Mat. Mekh., 2018 Number 4, Pages 54–56 (Mi vmumm562)

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The paranormality of products and their subsets

A. V. Bogomolov

Lomonosov Moscow State University, Faculty of Mechanics and Mathematics

Abstract: A topological space is called paranormal if any countable discrete system of closed sets $\{D_n{:}n=1,2,3,\ldots\}$ can be expanded to a locally finite system of open sets $\{U_n{:}n=1,2,3,\ldots\}$, i.e., $D_n$ is contained in $U_n$ for all $n$ and $D_m\cap U_n\neq\emptyset$ if and only if $D_m=D_n$. It is proved that if $X$ is a countably compact space whose cube is hereditarily paranormal, then $X$ is a metrizable space.

Key words: hereditarily paranormality, metrizability, Cartesian product, Cartesian cube, countable paracompactness.

UDC: 515.12

Received: 31.05.2017


 English version:
Moscow University Mathematics Bulletin, Moscow University Måchanics Bulletin, 2018, 73:4, 156–157

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