Definition 18.1.1 (Measurable Space).label Let $X$ be a set and $\cm \subset 2^{X}$ be a $\sigma$-algebra, then the pair $(X, \cm)$ is a measurable space.
Definition 18.1.1 (Measurable Space).label Let $X$ be a set and $\cm \subset 2^{X}$ be a $\sigma$-algebra, then the pair $(X, \cm)$ is a measurable space.