Skip to main content
2 of 3
added 120 characters in body
Wojowu
  • 28.2k
  • 3
  • 103
  • 185

Does existence of $\omega_1$ subset of reals imply $\omega_1$ choice for subsets of reals?

Suppose there exists a subset of $\Bbb R$ which has cardinality $\omega_1$. Is it then necessarilly true that for every collection of $\omega_1$ subsets of $\Bbb R$ there exists a choice function?

I suppose that the answer for the above question is no, just like existence of countable subsets of $\Bbb R$ doesn't imply countable choice for $\Bbb R$. However, I suppose, every proof would either need explicit use of forcing, or a model of ZF which already has some weird properties, like amorphous sets or something.

Note that, obviously, we assume that AC doesn't necessarilly hold.

I added "forcing" tag, because I believe this is what answer requires. If it's not the case, feel free to remove it.

Wojowu
  • 28.2k
  • 3
  • 103
  • 185