We have the following indirect implication of form equivalence classes:
| Implication | Reference |
|---|---|
| 133 \(\Rightarrow\) 231 | note-123 |
| 231 \(\Rightarrow\) 151 | 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. |
| 231: | \(UT(WO,WO,WO)\): The union of a well ordered collection of well orderable sets is well orderable. |
| 151: | \(UT(WO,\aleph_{0},WO)\) (\(U_{\aleph_{1}}\)): The union of a well ordered set of denumerable sets is well orderable. (If \(\kappa\) is a well ordered cardinal, see note 27 for \(UT(WO,\kappa,WO)\).) |
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