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 \(\Rightarrow\) 285 |
On functions without fixed points, Wi'sniewski, K. 1973, Comment. Math. Prace Mat. |
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. |
| 285: | Let \(E\) be a set and \(f: E\to E\), then \(f\) has a fixed point if and only if \(E\) is not the union of three mutually disjoint sets \(E_1\), \(E_2\) and \(E_3\) such that \(E_i \cap f(E_i) = \emptyset\) for \(i=1, 2, 3\). |
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