Timeline for "Gaps" in the Rudin-Keisler ordering
Current License: CC BY-SA 3.0
3 events
| when toggle format | what | by | license | comment | |
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| Aug 8, 2023 at 21:54 | comment | added | Andreas Blass | The existence of Ramsey ultrafilters is independent of ZFC. Do you know what happens if there are no Ramsey ultrafilters? (If the OP had forgotten to say "non-principal" in the question, this would be trivial: The bottom element of the RK order (the class of principal ultrafilters) would not be the lower part of a gap. | |
| Nov 3, 2017 at 7:18 | vote | accept | Dominic van der Zypen | ||
| Nov 2, 2017 at 23:10 | history | answered | Jing Zhang | CC BY-SA 3.0 |