minor edit

book.tex

@@ -904,21 +904,21 @@ following grammar.
 
 
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-\chapter{Compiling Integers and Variables}
+\chapter{Integers and Variables}
 \label{ch:int-exp}
 
-This chapter concerns the challenge of compiling a subset of Racket,
-which we name $R_1$, to x86-64 assembly code~\citep{Intel:2015aa}.
-(Henceforth we shall refer to x86-64 simply as x86).  The chapter
-begins with a description of the $R_1$ language (Section~\ref{sec:s0})
-and then a description of x86 (Section~\ref{sec:x86}). The
-x86 assembly language is quite large, so we only discuss what is
-needed for compiling $R_1$. We introduce more of x86 in later
-chapters. Once we have introduced $R_1$ and x86, we reflect on
-their differences and come up with a plan to break down the
-translation from $R_1$ to x86 into a handful of steps
-(Section~\ref{sec:plan-s0-x86}).  The rest of the sections in this
-Chapter give detailed hints regarding each step
+This chapter concerns the challenge of compiling a subset of Racket
+that includes integer arithmetic and local variable binding, which we
+name $R_1$, to x86-64 assembly code~\citep{Intel:2015aa}.  Henceforth
+we shall refer to x86-64 simply as x86.  The chapter begins with a
+description of the $R_1$ language (Section~\ref{sec:s0}) followed by a
+description of x86 (Section~\ref{sec:x86}). The x86 assembly language
+is quite large, so we only discuss what is needed for compiling
+$R_1$. We introduce more of x86 in later chapters. Once we have
+introduced $R_1$ and x86, we reflect on their differences and come up
+with a plan to break down the translation from $R_1$ to x86 into a
+handful of steps (Section~\ref{sec:plan-s0-x86}).  The rest of the
+sections in this Chapter give detailed hints regarding each step
 (Sections~\ref{sec:uniquify-s0} through \ref{sec:patch-s0}).  We hope
 to give enough hints that the well-prepared reader can implement a
 compiler from $R_1$ to x86 while at the same time leaving room for