Integral of Integrable Function is Monotone

Theorem
Let $\struct {X, \Sigma, \mu}$ be a measure space.

Let $f, g: X \to \overline \R$ be $\mu$-integrable functions.

Suppose that $f \le g$ pointwise.

Then:


 * $\displaystyle \int f \rd \mu \le \int g \rd \mu$