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 \(\Rightarrow\) 342-n | 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: | \(C(\aleph_{0},\infty)\): |
342-n: | (For \(n\in\omega\), \(n\ge 2\).) \(PC(\infty,n,\infty)\): Every infinite family of \(n\)-element sets has an infinite subfamily with a choice function. (See Form 166.) |
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