When $U(\kappa )$ can be mapped onto $U(\omega )$
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- by Jan van Mill PDF
- Proc. Amer. Math. Soc. 80 (1980), 701-702 Request permission
Abstract:
$U(\kappa )$ can be mapped onto $U(\omega ){\text {iff}}\;{\text {cf}}(\kappa ) = \omega {\text {or}}\kappa \geqslant {2^\omega }.$.References
- James E. Baumgartner, Almost-disjoint sets, the dense set problem and the partition calculus, Ann. Math. Logic 9 (1976), no. 4, 401–439. MR 401472, DOI 10.1016/0003-4843(76)90018-8
- W. W. Comfort and S. Negrepontis, The theory of ultrafilters, Die Grundlehren der mathematischen Wissenschaften, Band 211, Springer-Verlag, New York-Heidelberg, 1974. MR 0396267, DOI 10.1007/978-3-642-65780-1 E. K. van Douwen, Transfer of information about $\beta N - N$ via open remainder maps (to appear).
Additional Information
- © Copyright 1980 American Mathematical Society
- Journal: Proc. Amer. Math. Soc. 80 (1980), 701-702
- MSC: Primary 54A25; Secondary 04A20, 54D40
- DOI: https://doi.org/10.1090/S0002-9939-1980-0587959-4
- MathSciNet review: 587959