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Nov 7, 2022 at 21:28 comment added François G. Dorais @LSpice The quotient of $\mathbb{C}^n$ under permutation of coordinates.
Nov 7, 2022 at 18:31 comment added LSpice @FrançoisG.Dorais, what is the topology on multisets according to which that function is continuous?
Jun 21, 2012 at 22:29 comment added François G. Dorais I was looking for a reference for this result of Ernst Specker, here it is: MR0256880 ams.org/mathscinet-getitem?mr=256880 Note that the result is peculiar: For each $m \geq 1$ there is a continuous function that returns the $m$-element multiset of the roots of the (not necessarily irreducible) polynomial of degree $m$, but there is no continuous function that picks just one element from that multiset except in the case $m = 1$!
Jun 21, 2012 at 22:27 history edited Goldstern CC BY-SA 3.0
example of a choice without AC
Jun 21, 2012 at 21:15 history answered Goldstern CC BY-SA 3.0