Let $E\subset[a,b]$ be a non-mensurable set. I want to show that:
$\exists F \in F_\sigma$ : $F\subset E$ , $\mu^*(F)=\mu_*(E)$ .
Let $E\subset[a,b]$ be a non-mensurable set. I want to show that:
$\exists F \in F_\sigma$ : $F\subset E$ , $\mu^*(F)=\mu_*(E)$ .