Let $M = (X, \mathcal{F}, \mu)$ be a D1158: Measure space such that

(i)	$\text{MS} = \text{MS}(X \to [0, \infty])$ is the D2958: Set of measurable simple functions on $M$
(ii)	$f : X \to [0, \infty]$ is a D313: Measurable function on $M$

The unsigned basic integral of $f$ with respect to $M$ is the D5237: Unsigned basic number \begin{equation} \int_X f \, d \mu : = \sup \left\{ \int_X \phi \, d \mu \mid \phi \in \text{MS} \text{ such that } 0 \leq \phi \leq f \right\} \end{equation}