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Transactions of the American Mathematical Society

Published by the American Mathematical Society since 1900, Transactions of the American Mathematical Society is devoted to longer research articles in all areas of pure and applied mathematics.

ISSN 1088-6850 (online) ISSN 0002-9947 (print)

The 2020 MCQ for Transactions of the American Mathematical Society is 1.48.

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On perfect measures
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by G. Koumoullis PDF
Trans. Amer. Math. Soc. 264 (1981), 521-537 Request permission

Abstract:

Let $\mu$ be a nonzero positive perfect measure on a $\sigma$-algebra of subsets of a set $X$. It is proved that if $\{ {A_i}:i \in I\}$ is a partition of $X$ with ${\mu ^ \ast }({A_i}) = 0$ for all $i \in I$ and the cardinal of $I$ non-(Ulam-) measurable, then there is $J \subset I$ such that ${ \cup _{_{i \in J}}}{A_i}$ is not $\mu$-measurable, generalizing a theorem of Solovay about the Lebesgue measure. This result is used for the study of perfect measures on topological spaces. It is proved that every perfect Borel measure on a metric space is tight if and only if the cardinal of the space is nonmeasurable. The same result is extended to some nonmetric spaces and the relation between perfectness and other smoothness properties of measures on topological spaces is investigated.
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Additional Information
  • © Copyright 1981 American Mathematical Society
  • Journal: Trans. Amer. Math. Soc. 264 (1981), 521-537
  • MSC: Primary 28C15; Secondary 03E55, 54D18, 60A99
  • DOI: https://doi.org/10.1090/S0002-9947-1981-0603778-X
  • MathSciNet review: 603778