We have the following indirect implication of form equivalence classes:
Implication | Reference |
---|---|
192 \(\Rightarrow\) 43 |
Injectivity, projectivity and the axiom of choice, Blass, A. 1979, Trans. Amer. Math. Soc. |
43 \(\Rightarrow\) 8 | clear |
8 \(\Rightarrow\) 27 | clear |
27 \(\Rightarrow\) 31 | clear |
31 \(\Rightarrow\) 34 | clear |
34 \(\Rightarrow\) 104 | clear |
Here are the links and statements of the form equivalence classes referenced above:
Howard-Rubin Number | Statement |
---|---|
192: | \(EP\) sets: For every set \(A\) there is a projective set \(X\) and a function from \(X\) onto \(A\). |
43: | \(DC(\omega)\) (DC), Principle of Dependent Choices: If \(S\) is a relation on a non-empty set \(A\) and \((\forall x\in A) (\exists y\in A)(x S y)\) then there is a sequence \(a(0), a(1), a(2), \ldots\) of elements of \(A\) such that \((\forall n\in\omega)(a(n)\mathrel S a(n+1))\). See Tarski [1948], p 96, Levy [1964], p. 136. |
8: | \(C(\aleph_{0},\infty)\): |
27: | \((\forall \alpha)( UT(\aleph_{0},\aleph_{\alpha}, \aleph_{\alpha}))\): The union of denumerably many sets each of power \(\aleph_{\alpha }\) has power \(\aleph_{\alpha}\). Moore, G. [1982], p 36. |
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. |
104: | There is a regular uncountable aleph. Jech [1966b], p 165 prob 11.26. |
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