We have the following indirect implication of form equivalence classes:
| Implication | Reference |
|---|---|
| 164 \(\Rightarrow\) 91 |
Dedekind-Endlichkeit und Wohlordenbarkeit, Brunner, N. 1982a, Monatsh. Math. |
| 91 \(\Rightarrow\) 79 | clear |
| 79 \(\Rightarrow\) 70 | clear |
| 70 \(\Rightarrow\) 206 | clear |
| 206 \(\Rightarrow\) 223 | clear |
Here are the links and statements of the form equivalence classes referenced above:
| Howard-Rubin Number | Statement |
|---|---|
| 164: | Every non-well-orderable set has an infinite subset with a Dedekind finite power set. |
| 91: | \(PW\): The power set of a well ordered set can be well ordered. |
| 79: | \({\Bbb R}\) can be well ordered. Hilbert [1900], p 263. |
| 70: | There is a non-trivial ultrafilter on \(\omega\). Jech [1973b], prob 5.24. |
| 206: | The existence of a non-principal ultrafilter: There exists an infinite set \(X\) and a non-principal ultrafilter on \(X\). |
| 223: | There is an infinite set \(X\) and a non-principal measure on \(\cal P(X)\). |
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