We have the following indirect implication of form equivalence classes:
| Implication | Reference |
|---|---|
| 16 \(\Rightarrow\) 352 |
On first and second countable spaces and the axiom of choice, Gutierres, G 2004, Topology and its Applications. |
| 352 \(\Rightarrow\) 31 |
On first and second countable spaces and the axiom of choice, Gutierres, G 2004, Topology and its Applications. |
| 31 \(\Rightarrow\) 34 | clear |
| 34 \(\Rightarrow\) 19 |
Sur les fonctions representables analytiquement, Lebesgue, H. 1905, J. Math. Pures Appl. |
Here are the links and statements of the form equivalence classes referenced above:
| Howard-Rubin Number | Statement |
|---|---|
| 16: | \(C(\aleph_{0},\le 2^{\aleph_{0}})\): Every denumerable collection of non-empty sets each with power \(\le 2^{\aleph_{0}}\) has a choice function. |
| 352: | A countable product of second countable spaces is second countable. |
| 31: | \(UT(\aleph_{0},\aleph_{0},\aleph_{0})\): The countable union theorem: The union of a denumerable set of denumerable sets is denumerable. |
| 34: | \(\aleph_{1}\) is regular. |
| 19: | A real function is analytically representable if and only if it is in Baire's classification. G.Moore [1982], equation (2.3.1). |
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