We have the following indirect implication of form equivalence classes:
Implication | Reference |
---|---|
3 \(\Rightarrow\) 9 |
Cardinal addition and the axiom of choice, Howard, P. 1974, Bull. Amer. Math. Soc. |
9 \(\Rightarrow\) 64 |
The independence of various definitions of finiteness, Levy, A. 1958, Fund. Math. clear |
Here are the links and statements of the form equivalence classes referenced above:
Howard-Rubin Number | Statement |
---|---|
3: | \(2m = m\): For all infinite cardinals \(m\), \(2m = m\). |
9: | Finite \(\Leftrightarrow\) Dedekind finite: \(W_{\aleph_{0}}\) Jech [1973b]: \(E(I,IV)\) Howard/Yorke [1989]): Every Dedekind finite set is finite. |
64: | \(E(I,Ia)\) There are no amorphous sets. (Equivalently, every infinite set is the union of two disjoint infinite sets.) |
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