Journal of Symbolic Logic
- J. Symbolic Logic
- Volume 73, Issue 3 (2008), 817-823.
Regular ultrafilters and finite square principles
We show that many singular cardinals λ above a strongly compact cardinal have regular ultrafilters D that violate the finite square principle □finλ,D introduced in . For such ultrafilters D and cardinals λ there are models of size λ for which Mλ/D is not λ++-universal and elementarily equivalent models M and N of size λ for which Mλ/D and Nλ/D are non-isomorphic. The question of the existence of such ultrafilters and models was raised in .
J. Symbolic Logic, Volume 73, Issue 3 (2008), 817-823.
First available in Project Euclid: 27 December 2008
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Kennedy, Juliette; Shelah, Saharon; Väänänen, Jouko. Regular ultrafilters and finite square principles. J. Symbolic Logic 73 (2008), no. 3, 817--823. doi:10.2178/jsl/1230396748. https://projecteuclid.org/euclid.jsl/1230396748