We have the following indirect implication of form equivalence classes:
| Implication | Reference |
|---|---|
| 14 \(\Rightarrow\) 49 |
A survey of recent results in set theory, Mathias, A.R.D. 1979, Period. Math. Hungar. |
| 49 \(\Rightarrow\) 30 | clear |
| 30 \(\Rightarrow\) 62 | clear |
| 62 \(\Rightarrow\) 283 |
The well-ordered and well-orderable subsets of a set, Truss, J. K. 1973d, Z. Math. Logik Grundlagen Math. |
Here are the links and statements of the form equivalence classes referenced above:
| Howard-Rubin Number | Statement |
|---|---|
| 14: | BPI: Every Boolean algebra has a prime ideal. |
| 49: | Order Extension Principle: Every partial ordering can be extended to a linear ordering. Tarski [1924], p 78. |
| 30: | Ordering Principle: Every set can be linearly ordered. |
| 62: | \(C(\infty,< \aleph_{0})\): Every set of non-empty finite sets has a choice function. |
| 283: | Cardinality of well ordered subsets: For all \(n\in\omega\) and for all infinite \(x\), \(|x^n| < |s(x)|\) where \(s(x)\) is the set of all well orderable subsets of \(x\). |
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