\begin{definition}[Definition:Null Set/Signed Measure]
Let $\struct {X, \Sigma}$ be a measurable space.
Let $\mu$ be a signed measure on $\struct {X, \Sigma}$. 
Let $N \in \Sigma$.
We say that $N$ is a '''$\mu$-null set''' {{iff}}:
:for each $A \in \Sigma$ with $A \subseteq N$, we have $\map \mu A = 0$
Category:Definitions/Signed Measures
\end{definition}