Example 7.4.13(d): Measurable Functions
Show that a function f is measurable if and only if
- the set { x: f(x) < a } is measurable for all a
- the set { x: f(x) a } is measurable for all a
- the set { x: f(x) > a } is measurable for all a
- the set { x: f(x) a } is measurable for all a