Let $M = (X, \mathcal{F}, \mu, T)$ be a D2827: Measure-preserving system such that

(i)	$E \in \mathcal{F}$ is a D1109: Measurable set in $M$
(ii)	\begin{equation} T^{-1}(E) = E \end{equation}

Then \begin{equation} T^{-1}(X \setminus E) = X \setminus E \end{equation}