We have the following indirect implication of form equivalence classes:
| Implication | Reference |
|---|---|
| 391 \(\Rightarrow\) 392 | clear |
| 392 \(\Rightarrow\) 393 | clear |
| 393 \(\Rightarrow\) 121 | clear |
| 121 \(\Rightarrow\) 122 | clear |
| 122 \(\Rightarrow\) 250 | clear |
| 250 \(\Rightarrow\) 111 | clear |
Here are the links and statements of the form equivalence classes referenced above:
| Howard-Rubin Number | Statement |
|---|---|
| 391: | \(C(\infty,LO)\): Every set of non-empty linearly orderable sets has a choice function. |
| 392: | \(C(LO,LO)\): Every linearly ordered set of linearly orderable sets has a choice function. |
| 393: | \(C(LO,WO)\): Every linearly ordered set of non-empty well orderable sets has a choice function. |
| 121: | \(C(LO,<\aleph_{0})\): Every linearly ordered set of non-empty finite sets has a choice function. |
| 122: | \(C(WO,<\aleph_{0})\): Every well ordered set of non-empty finite sets has a choice function. |
| 250: | \((\forall n\in\omega-\{0,1\})(C(WO,n))\): For every natural number \(n\ge 2\), every well ordered family of \(n\) element sets has a choice function. |
| 111: | \(UT(WO,2,WO)\): The union of an infinite well ordered set of 2-element sets is an infinite well ordered set. |
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