updates

book.tex

@@ -1951,16 +1951,19 @@ Test your \key{uniquify} pass by creating five example $R_1$ programs
 and checking whether the output programs produce the same result as
 the input programs. The $R_1$ programs should be designed to test the
 most interesting parts of the \key{uniquify} pass, that is, the
-programs should include \key{let} forms, variables, and variables
-that overshadow each other.  The five programs should be in a
-subdirectory named \key{tests} and they should have the same file name
-except for a different integer at the end of the name, followed by the
-ending \key{.rkt}.  Use the \key{interp-tests} function
+programs should include \key{let} forms, variables, and variables that
+overshadow each other.  The five programs should be in a subdirectory
+named \key{tests} and they should have the same file name except for a
+different integer at the end of the name, followed by the ending
+\key{.rkt}. Use the \key{interp-tests} function
 (Appendix~\ref{appendix:utilities}) from \key{utilities.rkt} to test
 your \key{uniquify} pass on the example programs.  See the
-\key{run-tests.rkt} script in the student support code for an example
-of how to use \key{interp-tests}.
-
+\key{run-tests.rkt} script in the support code for an example of how
+to use \key{interp-tests}. The support code is in a \code{github}
+repository at the following URL:
+\begin{center}\footnotesize
+  \url{https://github.com/IUCompilerCourse/public-student-support-code}
+\end{center}
 \end{exercise}
 
 \section{Remove Complex Operands}
@@ -4175,8 +4178,8 @@ checker enforces the rule that the argument of \code{not} must be a
 
 The type checker for $R_2$ is a structurally recursive function over
 the AST. Figure~\ref{fig:type-check-R2} defines the
-\code{type-check-exp} function. The code for the type checker is
-included in the student support code.
+\code{type-check-exp} function. The code for the type checker is in
+the file \code{type-check-R2.rkt} of support code.
 %
 Given an input expression \code{e}, the type checker either returns a
 type (\key{Integer} or \key{Boolean}) or it signals an error.  The