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Strongly compact cardinals, elementary embeddings and fixed points

Published online by Cambridge University Press:  12 March 2014

Yoshihiro Abe*
Affiliation:
Fukushima Technical College, Iwaki-City Fukushima, 970, Japan

Extract

J. Barbanel [1] characterized the class of cardinals fixed by an elementary embedding induced by a normal ultrafilter on Pκλ assuming that κ is supercompact. In this paper we shall prove the same results from the weaker hypothesis that κ is strongly compact and the ultrafilter is fine.

We work in ZFC throughout. Our set-theoretic notation is quite standard. In particular, if X is a set, ∣X∣ denotes the cardinality of X and P(X) denotes the power set of X. Greek letters will denote ordinals. In particular γ, κ, η and γ will denote cardinals. If κ and λ are cardinals, then λ<κ is defined to be supγ<κγγ. Cardinal exponentiation is always associated from the top. Thus, for example, 2λ<κ means 2(λ<κ). V denotes the universe of all sets. If M is an inner model of ZFC, ∣XM and P(X)M denote the cardinality of X in M and the power set of X in M respectively.

We review the basic facts on fine ultrafilters and the corresponding elementary embeddings. (For detail, see [2].)

Definition. Assume κ and λ are cardinals with κλ. Then, Pκλ = {Xλ∣∣X∣ < κ}.

It is important to note that ∣Pκλ∣ = λ< κ.

Type
Research Article
Copyright
Copyright © Association for Symbolic Logic 1984

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References

REFERENCES

[1]Barbanel, J. B., Supercompact cardinals, elementary embeddings and fixed points, this Journal, vol. 47 (1982), pp. 8488.Google Scholar
[2]Solovay, R. M., Reinhardt, W. N. and Kanamori, A., Strong axioms of infinity and elementary embeddings, Annals of Mathematical Logic, vol. 13 (1978), pp. 73116.CrossRefGoogle Scholar
[3]Solovay, R. M., Strongly compact cardinals and the GCH, Proceedings of the Tarski Symposium (Henkin, L.et al., editors). Proceedings of Symposia in Pure Mathematics, vol. 25, American Mathematical Society, Providence, Rhode Island, 1974, pp. 365372.CrossRefGoogle Scholar