Added the Mackey-Arens theorem.

src/fa/duality/polar.tex

@@ -127,3 +127,15 @@
     Therefore $y \in A^{\circ}$, but $\text{Re}\dpn{x_0, y}{\lambda} > 1$, so $x_0 \not\in A^{\circ\circ}$.
 \end{proof}
 
+\begin{proposition}
+\label{proposition:polar-equicontinuous}
+    Let $E$ be a locally convex space, then:
+    \begin{enumerate}
+        \item For each equicontinuous family $\cf \subset E^*$ equicontinuous, $\cf^\circ \in \cn_E(0)$. 
+        \item For each $U \in \cn_E(0)$, $U^\circ$ is equicontinuous. 
+    \end{enumerate}
+\end{proposition}
+
+
+
+