Added the Mackey-Arens theorem.

src/topology/uniform/equicontinuous.tex

@@ -49,12 +49,12 @@
 
     In addition, if $\cf$ satisfies (E1) and
     \begin{enumerate}[label=(E\arabic*), start=1]
-        \item For each $x \in X$, $\cf(x) = \bracs{f(x)|f \in \cf}$ is precompact in $Y$.
+        \item For each $x \in X$, $\cf(x) = \bracs{f(x)|f \in \cf}$ is relatively compact in $Y$.
     \end{enumerate}
 
     then
     \begin{enumerate}[label=(C\arabic*), start=2]
-        \item $\cf$ is a precompact subset of $C(X; Y)$ with respect to the uniform structure of compact convergence. 
+        \item $\cf$ is a relatively compact subset of $C(X; Y)$ with respect to the uniform structure of compact convergence. 
     \end{enumerate}
 
     Conversely, if $X$ is a LCH space, then (C3) implies (E1) + (E2).