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David Feldman
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Cantor's diagonalization construction, on a certain view, furnishes functions $$d_X:{\rm Injections}(X,P(X))\rightarrow P(X)$$ that satisfy $\forall X\forall i\ \ d_X(i)\not\in i(X)$

In ZF, can one prove the existence of such functions with the added requirement that $d_x(i)$$d_X(i)$ actually depends only on the image $i(X)$?

Cantor's diagonalization construction, on a certain view, furnishes functions $$d_X:{\rm Injections}(X,P(X))\rightarrow P(X)$$ that satisfy $\forall X\forall i\ \ d_X(i)\not\in i(X)$

In ZF, can one prove the existence of such functions with the added requirement that $d_x(i)$ actually depends only on the image $i(X)$?

Cantor's diagonalization construction, on a certain view, furnishes functions $$d_X:{\rm Injections}(X,P(X))\rightarrow P(X)$$ that satisfy $\forall X\forall i\ \ d_X(i)\not\in i(X)$

In ZF, can one prove the existence of such functions with the added requirement that $d_X(i)$ actually depends only on the image $i(X)$?

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Asaf Karagila
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David Feldman
  • 17.6k
  • 8
  • 67
  • 135

Cantor's diagonal argument and ZF

Cantor's diagonalization construction, on a certain view, furnishes functions $$d_X:{\rm Injections}(X,P(X))\rightarrow P(X)$$ that satisfy $\forall X\forall i\ \ d_X(i)\not\in i(X)$

In ZF, can one prove the existence of such functions with the added requirement that $d_x(i)$ actually depends only on the image $i(X)$?