Changes to intro to spec lecture, motivated by suggestions from @mcdona16 and scimed1

Lectures/L21_IntroToSpecification/IntroToSpecification.tex

@@ -294,10 +294,10 @@ Which of the following implements mystery(j) in Python?
 
 \bi
 \item $\{ p: \mbox{pointT} | x_{\mbox{left}} \leq p.\mbox{xcrd}() \leq
-  x_{\mbox{left}} + \mbox{width} \wedge y_{\mbox{bot}} \leq p.\mbox{ycrd}() \leq
-  y_{\mbox{bot}} + \mbox{height} : p \}$
+  (x_{\mbox{left}} + \mbox{width}) \wedge y_{\mbox{bot}} \leq p.\mbox{ycrd}() \leq
+  (y_{\mbox{bot}} + \mbox{height}) : p \}$
 \item \structure<1>{What does this notation mean?}
-\item \uncover<2->{\structure<2>{Set of all points inside a box, including the boundaries}}
+\item \uncover<2->{\structure<2>{Set of all points inside a rectangle, including the boundaries}}
 \ei
 
 \end{frame}
@@ -312,7 +312,7 @@ Which of the following implements mystery(j) in Python?
   p_1 + (1 - t) p_2) \leq c.\mbox{rad}())$
 \item \structure<1>{What does this notation mean?}
 \item \uncover<2->{\structure<2>{True if the line and the circle overlap at
-      least one point}}
+      at least one point}}
 \ei
 
 \end{frame}
@@ -397,8 +397,10 @@ Which of the following implements mystery(j) in Python?
 \item Major failures occur because of misunderstandings between the producer and
   the user
 \item ``The hardest single part of building a software system is deciding
-  precisely what to build'' (F.\ Brooks)
-\item Precise description of the borderline bw the machine and the
+  precisely what to build''
+  (\href{https://gitlab.cas.mcmaster.ca/smiths/se2aa4_cs2me3/blob/master/ReferenceMaterial/Brooks1987.pdf}
+  {Brooks1987})
+\item Precise description of the borderline b/w the machine and the
   \structure{environment} (end user and other systems)
 \end{itemize}
 \item Statement of interface between the machine and the controlled environment
@@ -406,7 +408,7 @@ Which of the following implements mystery(j) in Python?
 \item Serious undesirable effects can result due to misunderstandings between
   software engineers and domain experts about the phenomena affecting the
   control function to be implemented by software
-\item Precise description of the borderline between the machine and the
+\item Precise description of the borderline b/w the machine and the
   \structure{environment} (devices controlled by machines)
 \end{itemize}
 \end{itemize}