Post-class fixes

Advanced/De Bruijn/parts/4 sturmian.tex

@@ -176,7 +176,7 @@ Show that each of the following is possible:
 Construct $R_2$ by removing one edge from $G_2$, then construct $\mathcal{L}(R_2)$. \par
 \begin{itemize}
 	\item If this line graph has four edges, set $R_3 = \mathcal{L}(R_2)$. \par
-	\item If not, remove one edge from $R_2$ so that an Eulerian path still exists
+	\item If not, remove one edge from $\mathcal{L}(R_2)$ so that an Eulerian path still exists
 	and set $R_3$ to the resulting graph.
 \end{itemize}
 Label each edge in $R_3$ with the last letter of its target node. \par