We have the following indirect implication of form equivalence classes:
| Implication | Reference |
|---|---|
| 264 \(\Rightarrow\) 202 |
Variations of Zorn's lemma, principles of cofinality, and Hausdorff's maximal principle, Part I and II, Harper, J. 1976, Notre Dame J. Formal Logic |
| 202 \(\Rightarrow\) 40 | clear |
| 40 \(\Rightarrow\) 39 | clear |
| 39 \(\Rightarrow\) 8 | clear |
| 8 \(\Rightarrow\) 355 | clear |
Here are the links and statements of the form equivalence classes referenced above:
| Howard-Rubin Number | Statement |
|---|---|
| 264: | \(H(C,P)\): Every connected relation \((X,R)\) contains a \(\subseteq\)-maximal partially ordered set. |
| 202: | \(C(LO,\infty)\): Every linearly ordered family of non-empty sets has a choice function. |
| 40: | \(C(WO,\infty)\): Every well orderable set of non-empty sets has a choice function. Moore, G. [1982], p 325. |
| 39: | \(C(\aleph_{1},\infty)\): Every set \(A\) of non-empty sets such that \(\vert A\vert = \aleph_{1}\) has a choice function. Moore, G. [1982], p. 202. |
| 8: | \(C(\aleph_{0},\infty)\): |
| 355: | \(KW(\aleph_0,\infty)\), The Kinna-Wagner Selection Principle for a denumerable family of sets: For every denumerable set \(M\) there is a function \(f\) such that for all \(A\in M\), if \(|A| > 1\) then \(\emptyset\neq f(A)\subsetneq A\). |
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