Correct quotes

main.tex

@@ -146,7 +146,7 @@
 		\item But $\phi(\bigO_X) \not= \phi(\bigO_X[2])$
 		\item Stability decided among $E \in D^b(X) \colon \phi(E) \in (0, \pi] =
 			\coh(X)$ \\
-			($\phi$ only partial "function")
+			($\phi$ only partial ``function'')
 	\end{itemize}
 \end{frame}