added
authorChristian Urban <christian dot urban at kcl dot ac dot uk>
Sat, 26 Oct 2013 00:49:14 +0100
changeset 156 95eaee695636
parent 155 9b2d128765e1
child 157 b6eee9571a63
added
handouts/ho05.pdf
handouts/ho05.tex
Binary file handouts/ho05.pdf has changed
--- a/handouts/ho05.tex	Sat Oct 26 00:39:27 2013 +0100
+++ b/handouts/ho05.tex	Sat Oct 26 00:49:14 2013 +0100
@@ -198,10 +198,19 @@
 \end{center}
 
 \noindent
-Clearly, this string should clearly be identified as a keyword. The problem is that also the regular expression \textit{IDENT} for identifiers would also match this string. To solve this ambiguity we need to rank our regular expressions.
+Clearly, this string should clearly be identified as a keyword. The problem is that also the regular expression \textit{IDENT} for identifiers would also match this string. To overcome this ambiguity we need to rank our 
+regular expressions. In our running example we just use the ranking
+
+\[
+\textit{KEYWORD} < \textit{IDENT} < \textit{OP} < \ldots
+\]
 
+\noindent
+and so on. So even if both regular expressions match in the example above,
+we can give the regular expression for \ref{Page ??} as follows
 
-
+Let us see how our algorithm for lexing works in detail. The regular 
+expressions and their ranking are shown above. 
 \end{document}
 
 %%% Local Variables: