Let $\emptyset$ be the D13: Empty set.
Let $X_1, \ldots, X_N$ each be a D11: Set such that
Let $X_1, \ldots, X_N$ each be a D11: Set such that
| (i) | \begin{equation} \exists \, n \in 1, \ldots, N : X_n = \emptyset \end{equation} |
Then
\begin{equation}
\bigcap_{n = 1}^N X_n
= \emptyset
\end{equation}