On nonmeasurable unions
For a Polish space X and a σ-ideal I of subsets of X which has a Borel base we consider families A of sets in I with the union ⋃ A not in I. We determine several conditions on A which imply the existence of a subfamily A ′ of A whose union ⋃ A ′ is not in the σ-field generated by the Borel sets on X...
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Published in | Topology and its applications Vol. 154; no. 4; pp. 884 - 893 |
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Main Authors | , , , , |
Format | Journal Article |
Language | English |
Published |
Elsevier B.V
15.02.2007
|
Subjects | |
Online Access | Get full text |
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Summary: | For a Polish space
X and a
σ-ideal I of subsets of
X which has a Borel base we consider families
A
of sets in
I with the union
⋃
A
not in
I. We determine several conditions on
A
which imply the existence of a subfamily
A
′
of
A
whose union
⋃
A
′
is not in the
σ-field generated by the Borel sets on
X and
I. Main examples are
X
=
R
and
I being the ideal of sets of Lebesgue measure zero or the ideal of sets of the first Baire category. |
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ISSN: | 0166-8641 1879-3207 |
DOI: | 10.1016/j.topol.2006.09.013 |