We have the following indirect implication of form equivalence classes:
| Implication | Reference |
|---|---|
| 7 \(\Rightarrow\) 9 |
On the existence of large sets of Dedekind cardinals, Tarski, A. 1965, Notices Amer. Math. Soc. The Axiom of Choice, Jech, 1973b, page 161 problem 11.6 |
| 9 \(\Rightarrow\) 13 | clear |
Here are the links and statements of the form equivalence classes referenced above:
| Howard-Rubin Number | Statement |
|---|---|
| 7: | There is no infinite decreasing sequence of cardinals. |
| 9: | Finite \(\Leftrightarrow\) Dedekind finite: \(W_{\aleph_{0}}\) Jech [1973b]: \(E(I,IV)\) Howard/Yorke [1989]): Every Dedekind finite set is finite. |
| 13: | Every Dedekind finite subset of \({\Bbb R}\) is finite. |
Comment: