How can I construct such a Borel subset?
3023
Construction of a Borel set with positive but not full measure in each interval
51134
If $E \in \sigma(\mathcal{C})$ then there exists a countable subset $\mathcal{C}_0 \subseteq \mathcal{C}$ with $E \in \sigma(\mathcal{C}_0)$
129194
Correspondences between Borel algebras and topological spaces
45405
An elementary way to show any bounded subset of $\Bbb{R}^k$ is totally bounded
132025
Is there an alternative to Cantor's cardinalities that makes proper subsets smaller than their sets?
97064
Dense set in an infinite cofinite space
24749
Monotone functions and Borel sets
11082
Borel-Cantelli Lemma "Corollary" in Royden and Fitzpatrick
31710
Show that $\mathcal{J}=\{[a, a+1) \mid a \in \mathbb{R}\}$ generates the Borel set of $\mathbb{R}$
28468
Haar measure on $SO(n)$
1627
Cartesian product of an arbitrary number of sets
158018
Everywhere Super Dense Subset of $\mathbb{R}$
17764
What's the relationship between Borel set and set whose boundary is measure zero?
131037
Is every compact subset of $\Bbb{R}$ the support of some Borel measure?
153305
Adding subsets of regular cardinals (Jech p. 226)
6675
Lebesgue measurable set that is not a Borel measurable set
100977
Infinite subset with pairwise comprime elements