to do: free reduction rule

book.tex

@@ -3034,7 +3034,7 @@ store the type within the \key{program} form as shown in Figure
 programs is below:
 
 \fbox{
-\begin{minipage}{0.96\textwidth}
+\begin{minipage}{0.87\textwidth}
 \[
 \begin{array}{lcl}
   R_2 &::=& (\key{program}\;(\key{type}\;\textit{type})\; \Exp)