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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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The almost-disjointness number may have countable cofinality
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by Jörg Brendle PDF
Trans. Amer. Math. Soc. 355 (2003), 2633-2649 Request permission


We show that it is consistent for the almost-disjointness number $\mathfrak {a}$ to have countable cofinality. For example, it may be equal to $\aleph _\omega$.
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Additional Information
  • Jörg Brendle
  • Affiliation: The Graduate School of Science and Technology, Kobe University, Rokko–dai 1–1, Nada–ku, Kobe 657–8501, Japan
  • Email:
  • Received by editor(s): October 3, 2001
  • Published electronically: February 27, 2003
  • Additional Notes: Supported by Grant–in–Aid for Scientific Research (C)(2)12640124, Japan Society for the Promotion of Science
  • © Copyright 2003 American Mathematical Society
  • Journal: Trans. Amer. Math. Soc. 355 (2003), 2633-2649
  • MSC (2000): Primary 03E17; Secondary 03E35
  • DOI:
  • MathSciNet review: 1975392