On dimension of non-totally normal spaces (Q1174043)
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scientific article; zbMATH DE number 7986
| Language | Label | Description | Also known as |
|---|---|---|---|
| English | On dimension of non-totally normal spaces |
scientific article; zbMATH DE number 7986 |
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On dimension of non-totally normal spaces (English)
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25 June 1992
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In the class of normal spaces are considered the inductive dimensional invariants \(\text{Ind}_ 1\) and \(\text{ind}_ 1\), proposed by \textit{V. V. Filippov}, defined with the help of \(D\)-closed partitions, i.e. partitions, the complements of which are joins of a system of open sets, locally finite in these complements, of type \(F_ \sigma\) in the enveloping space. Briefly proved is the following sum theorem: If the sets \(F_ i\), \(i\in\mathbb{N}\), are \(D\)-closed in a normal space, then \(\text{Ind}_ 1\bigcup\{F_ i;\;i\in\mathbb{N}\}=\sup\{\text{Ind}_ 1 F_ i; i\in\mathbb{N}\}\). The following relations are stated: (1) \(\text{ind}_ 1\beta X\geq \text{Ind}_ 1 X\) for normal \(X\); (2) \(\text{ind}_ 1 X= \text{Ind}_ 1 X\) for completely paracompact \(X\); (3) \(\text{Ind}(X\times Y)\leq \text{Ind}_ 1 X+ \text{Ind}_ 1 Y\), if the product \(X\times Y\) is completely paracompact. (Translation from the Referativnyj Zhurnal Matematiki).
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inductve dimensional invariants
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