$\def\R{\mathbb R}$Let $A= \{x: f \text{ is continuous at $x$}\}$ for $f : \R\to \R$ , why is $A$ Borel measurable?
Why Continuity set is a borel set?
3
$\begingroup$
measure-theory
-
0Think about $\liminf$ and $\limsup$ – 2012-09-18