Abstract
A P-point ultrafilter over ω is called an interval P-point if for every function from ω to ω there exists a set A in this ultrafilter such that the restriction of the function to A is either a constant function or an interval-to-one function. In this paper we prove the following results. (1) Interval P-points are not isomorphism invariant under CH or MA. (2) We identify a cardinal invariant non∗ ∗(Iint) such that every filter base of size less than continuum can be extended to an interval P-point if and only if non∗ ∗(Iint) = c. (3) We prove the generic existence of slow/rapid non-interval P-points and slow/rapid interval P-points which are neither quasi-selective nor weakly Ramsey under the assumption d= c or cov(B) = c.
Original language | English |
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Pages (from-to) | 619-640 |
Number of pages | 22 |
Journal | Archive for Mathematical Logic |
Volume | 62 |
Issue number | 5-6 |
DOIs | |
State | Published - Jul 2023 |
Externally published | Yes |
Bibliographical note
Publisher Copyright:© 2022, The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.
Funding
Jialiang He: Supported in part by a National Science Foundation of China Grant #11801386. Renling Jin: Supported in part by a collaboration research Grant #513023 from Simons Foundation. Shuguo Zhang: Supported in part by a National Science Foundation of China Grant #11771311.
Funders | Funder number |
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Simons Foundation | |
National Natural Science Foundation of China | 11771311, 513023, 1180010236, 11801386 |
Keywords
- Generic existence
- Interval P-point
- P-point
- Quasi-selective ultrafilter
- Weakly Ramsey ultrafilter