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8 votes
1 answer
1k views

Worst of both worlds?

It's well known that $\mathsf{AC}$ implies the existence of non-measurable sets. And it's also true that, if all sets are measurable, then $|\mathbb{R}/\mathbb{Q}| > |\mathbb{R}|$. But is there a ...
Zemyla's user avatar
  • 309
15 votes
2 answers
2k views

Is "There exists an unbounded non-measurable set but no bounded non-measurable set" consistent with $\mathsf{ZF}$?

This is a follow-up to this question. We say that a set $A \subseteq \mathbb{R}$ is bounded if there exists a finite interval $(a,b)$ such that $A \subseteq (a,b)$. Working in $\mathsf{ZFC}$, the ...
Clement Yung's user avatar
  • 1,412
7 votes
1 answer
393 views

Models with fixed cardinality of non-Lebesgue measurable sets

In the usual $\mathsf{ZFC}$, we know that there are $2^\mathfrak{c}$ many subsets of $\mathbb{R}$ that are not (Lebesgue) measurable. On the other hand, the Solovay model also provides us a model of $\...
Clement Yung's user avatar
  • 1,412
1 vote
0 answers
150 views

Is there difference in notion of measurability in classical versus constructive?

Are there notions of measure and examples of sets measurable in that measure in classical logic but not in constructive logic (I think there cannot be counterexamples in other direction)? Are there ...
VS.'s user avatar
  • 1,826