The almost-disjointness number may have countable cofinality

Brendle, Jörg

doi:10.1090/S0002-9947-03-03271-9

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

Abstract:

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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