We have the following indirect implication of form equivalence classes:
| Implication | Reference |
|---|---|
| 90 \(\Rightarrow\) 91 | The Axiom of Choice, Jech, 1973b, page 133 |
| 91 \(\Rightarrow\) 79 | clear |
| 79 \(\Rightarrow\) 70 | clear |
| 70 \(\Rightarrow\) 206 | clear |
Here are the links and statements of the form equivalence classes referenced above:
| Howard-Rubin Number | Statement |
|---|---|
| 90: | \(LW\): Every linearly ordered set can be well ordered. Jech [1973b], p 133. |
| 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 \(X\). |
Comment: