On a theorem of Menkyna (Q1308864)
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scientific article; zbMATH DE number 465123
| Language | Label | Description | Also known as |
|---|---|---|---|
| English | On a theorem of Menkyna |
scientific article; zbMATH DE number 465123 |
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On a theorem of Menkyna (English)
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2 January 1994
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Let \(T_ d\) be the density topology of \(\mathbb R\) (\(\mathbb R\) -- the real line). The family \(T_{ae}\) of all sets \(A \in T_ d\) such that \(m(A - \text{int}\, A) = 0\) (\(m\) is the Lebesgue measure, \(\text{int}\,A\) denotes the Euclidean interior of \(A\)) is a topology said the a.e. topology [\textit{R. J. O'Malley}, Pac. J. Math. 72, 207--222 (1977; Zbl 0369.26003)]. A function \(f:(a,b) \to \mathbb R\), \((a,b) \subset \mathbb R\), is said to be a.e. continuous at a point \(x \in(a,b)\) if for every \(\varepsilon > 0\) there is a set \(B \in T_{ae}\) such that \(x \in B\) and \(f(B) \subset (f(x) - \varepsilon, f(x) + \varepsilon)\). The author gives a characterization of the set where an almost everywhere continuous Baire 1 function is a.e. continuous.
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density topology
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a.e. topology
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almost everywhere continuous Baire 1 function
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