We have the following indirect implication of form equivalence classes:
| Implication | Reference |
|---|---|
| 133 \(\Rightarrow\) 63 |
Dedekind-Endlichkeit und Wohlordenbarkeit, Brunner, N. 1982a, Monatsh. Math. |
| 63 \(\Rightarrow\) 221 | clear |
Here are the links and statements of the form equivalence classes referenced above:
| Howard-Rubin Number | Statement |
|---|---|
| 133: | Every set is either well orderable or has an infinite amorphous subset. |
| 63: |
\(SPI\): Weak ultrafilter principle: Every infinite set has a non-trivial ultrafilter.
|
| 221: | For all infinite \(X\), there is a non-principal measure on \(\cal P(X)\). |
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