Author:
Blass Andreas,Mildenberger Heike
Abstract
AbstractWe prove some restrictions on the possible cofinalities of ultrapowers of the natural numbers with respect to ultrafilters on the natural numbers. The restrictions involve three cardinal characteristics of the continuum, the splitting numbers, the unsplitting numberr, and the groupwise density numberg. We also prove some related results for reduced powers with respect to filters other than ultrafilters.
Publisher
Cambridge University Press (CUP)
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Cited by
23 articles.
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