 Absolute continuity of measures

A measure $\nu$ is absolutely continuous with respect to $\mu$, written $\nu \ll \mu$, when every $\mu$-null measurable set is also $\nu$-null. This is distinct from the regularity property of functions called absolute continuity.

A measure $\nu$ is absolutely continuous with respect to $\mu$ when every $\mu$-null set is also $\nu$-null.