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 \(\Rightarrow\) 146 |
The axiom of choice in topology, Brunner, N. 1983d, Notre Dame J. Formal Logic note-26 |
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. |
| 146: | \(A(F,A1)\): For every \(T_2\) topological space \((X,T)\), if \(X\) is a continuous finite to one image of an A1 space then \((X,T)\) is an A1 space. (\((X,T)\) is A1 means if \(U \subseteq T\) covers \(X\) then \(\exists f : X\rightarrow U\) such that \((\forall x\in X) (x\in f(x)).)\) |
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