Let \(X\) be a topological space and \(A\subseteq B\) subsets of \(X\). Then
\begin{equation*} \Int A \subseteq \Int B. \end{equation*}
Proof
According to (0x677a95f6)
we have \(\Int A \subseteq B\). Therefore, according to the definition
we obtain \(\Int A \subseteq \Int B\).