Consider some $D$ s.t. $\patchof{D} = \bot$. $D \neq B$
so $D \isin B \equiv D \isin L$.
-
-By Foreign Inclusion of $D$ xxx up to here
+By Foreign Inclusion of $D$ in $L$, $D \isin L \equiv D \le L$.
+And by Exact Ancestors $D \le L \equiv D \le B$.
+So $D \isin B \equiv D \le B$. $\qed$
\section{Create Tip}