# HG changeset patch
# User Christian Urban <christian dot urban at kcl dot ac dot uk>
# Date 1414919415 0
# Node ID 19f23c4c2167a402202ab20488904db47de340da
# Parent  c29853b672fb722c2e86fb808bfaf78b0ae55112
updated

diff -r c29853b672fb -r 19f23c4c2167 grammar.sty
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/grammar.sty	Sun Nov 02 09:10:15 2014 +0000
@@ -0,0 +1,4 @@
+\usepackage{listproc}
+\usepackage{plstx}
+
+\newcommand*{\meta}[1]{{\ensuremath{\langle}\textit{#1}\/\ensuremath{\rangle}}}
diff -r c29853b672fb -r 19f23c4c2167 progs/app7.scala
--- a/progs/app7.scala	Sat Nov 01 16:19:05 2014 +0000
+++ b/progs/app7.scala	Sun Nov 02 09:10:15 2014 +0000
@@ -2,8 +2,8 @@
   def parse(ts: I): Set[(T, I)]
 
   def parse_all(ts: I) : Set[T] =
-    for ((head, tail) <- parse(ts); if (tail.isEmpty)) 
-      yield head
+    for ((head, tail) <- parse(ts); 
+         if (tail.isEmpty)) yield head
 }
 
 
diff -r c29853b672fb -r 19f23c4c2167 slides.sty
--- a/slides.sty	Sat Nov 01 16:19:05 2014 +0000
+++ b/slides.sty	Sun Nov 02 09:10:15 2014 +0000
@@ -14,8 +14,6 @@
 \hypersetup{linkcolor=darkblue}
 \hypersetup{urlcolor=darkblue}
 
-
-
 \newcommand{\tttext}[1]{{\consolas{#1}}}
 
 \newcommand{\dn}{\stackrel{\mbox{\scriptsize def}}{=}}%
diff -r c29853b672fb -r 19f23c4c2167 slides/slides06.pdf
Binary file slides/slides06.pdf has changed
diff -r c29853b672fb -r 19f23c4c2167 slides/slides06.tex
--- a/slides/slides06.tex	Sat Nov 01 16:19:05 2014 +0000
+++ b/slides/slides06.tex	Sun Nov 02 09:10:15 2014 +0000
@@ -1,42 +1,25 @@
 \documentclass[dvipsnames,14pt,t]{beamer}
-\usepackage{beamerthemeplaincu}
-\usepackage[absolute,overlay]{textpos}
-\usepackage{ifthen}
-\usepackage{tikz}
-\usepackage{pgf}
-\usepackage{calc} 
-\usepackage{ulem}
-\usepackage{courier}
-\usepackage{listings}
-\renewcommand{\uline}[1]{#1}
-\usetikzlibrary{arrows}
-\usetikzlibrary{automata}
-\usetikzlibrary{shapes}
-\usetikzlibrary{shadows}
-\usetikzlibrary{positioning}
-\usetikzlibrary{calc}
-\usetikzlibrary{plotmarks}
-\usepackage{graphicx} 
+\usepackage{../slides}
+\usepackage{../graphics}
 \usepackage{../langs}
 \usepackage{../data}
+\usepackage{../grammar}
 
+\hfuzz=220pt 
 
-\makeatletter
-\lst@CCPutMacro\lst@ProcessOther {"2D}{\lst@ttfamily{-{}}{-{}}}
-\@empty\z@\@empty
-\makeatother
+\pgfplotsset{compat=1.11}
 
+\newcommand{\bl}[1]{\textcolor{blue}{#1}}  
 
 % beamer stuff 
-\renewcommand{\slidecaption}{AFL 06, King's College London, 30.~October 2013}
-\newcommand{\bl}[1]{\textcolor{blue}{#1}}       
-\newcommand{\dn}{\stackrel{\mbox{\scriptsize def}}{=}}% for definitions
+\renewcommand{\slidecaption}{AFL 06, King's College London}
 
 \begin{document}
 
+
+
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-\mode<presentation>{
-\begin{frame}<1>[t]
+\begin{frame}[t]
 \frametitle{%
   \begin{tabular}{@ {}c@ {}}
   \\[-3mm]
@@ -53,31 +36,56 @@
   \end{tabular}
   \end{center}
 
+\end{frame}
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%     
 
-\end{frame}}
- %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%     
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-\mode<presentation>{
 \begin{frame}[c]
-\frametitle{\begin{tabular}{c}Regular Languages\end{tabular}}
+\frametitle{Regular Languages}
 
-While regular expressions are very useful for lexing, 
-there is no regular expression that can recognise the language \bl{$a^nb^n$}.\bigskip
+While regular expressions are very useful for lexing, there is
+no regular expression that can recognise the language
+\bl{$a^nb^n$}.\bigskip
 
 \begin{center}
 \bl{$(((()()))())$} \;\;vs.\;\; \bl{$(((()()))()))$}
-\end{center}
+\end{center}\bigskip\bigskip
 
+\small
+\noindent So we cannot find out with regular expressions
+whether parentheses are matched or unmatched.
 
-\end{frame}}
+\end{frame}
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%   
 
-
-\newcommand{\qq}{\mbox{\texttt{"}}}
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-\mode<presentation>{
 \begin{frame}[c]
-\frametitle{\begin{tabular}{c}Grammars\end{tabular}}
+\frametitle{Hierarchy of Languages}
+
+\begin{center}
+\begin{tikzpicture}
+[rect/.style={draw=black!50, 
+              top color=white,
+              bottom color=black!20, 
+              rectangle, 
+              very thick, 
+              rounded corners}]
+
+\draw (0,0) node [rect, text depth=39mm, text width=68mm] {all languages};
+\draw (0,-0.4) node [rect, text depth=28.5mm, text width=64mm] {decidable languages};
+\draw (0,-0.85) node [rect, text depth=17mm] {context sensitive languages};
+\draw (0,-1.14) node [rect, text depth=9mm, text width=50mm] {context-free languages};
+\draw (0,-1.4) node [rect] {regular languages};
+\end{tikzpicture}
+
+\end{center}
+
+\end{frame}
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%   
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+\begin{frame}[c]
+\frametitle{Grammars}
 
 A (context-free) grammar \bl{$G$} consists of
 
@@ -99,14 +107,14 @@
 \end{center}
 \end{itemize}
 
-
-\end{frame}}
+\end{frame}
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%   
 
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-\mode<presentation>{
 \begin{frame}[c]
-\frametitle{\begin{tabular}{c}Palindromes\end{tabular}}
+\frametitle{Palindromes}
+
+A grammar for palindromes over the alphabet~\bl{$\{a,b\}$}:
 
 \begin{center}
 \bl{\begin{tabular}{lcl}
@@ -122,18 +130,17 @@
 \bl{\begin{tabular}{lcl}
 $S$ & $\rightarrow$ &  $\epsilon \;|\; a\cdot S\cdot a \;|\;b\cdot S\cdot b$ \\
 \end{tabular}}
-\end{center}
+\end{center}\pause\bigskip
 
+\small
+Can you find the grammar rules for matched parentheses?
 
-\end{frame}}
+\end{frame}
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%   
 
-
-
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-\mode<presentation>{
 \begin{frame}[c]
-\frametitle{\begin{tabular}{c}Arithmetic Expressions\end{tabular}}
+\frametitle{Arithmetic Expressions}
 
 \begin{center}
 \bl{\begin{tabular}{lcl}
@@ -147,15 +154,12 @@
 
 \bl{\texttt{1 + 2 * 3 + 4}}
 
-\end{frame}}
+\end{frame}
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%   
 
-
-
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-\mode<presentation>{
 \begin{frame}[c]
-\frametitle{\begin{tabular}{c}A CFG Derivation\end{tabular}}
+\frametitle{A CFG Derivation}
 
 \begin{enumerate}
 \item Begin with a string containing only the start symbol, say \bl{$S$}\bigskip
@@ -168,14 +172,12 @@
 \bl{$S \rightarrow \ldots \rightarrow \ldots  \rightarrow \ldots  \rightarrow \ldots $}
 \end{center}
 
-\end{frame}}
+\end{frame}
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 
   
-
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-\mode<presentation>{
 \begin{frame}[c]
-\frametitle{\begin{tabular}{c}Example Derivation\end{tabular}}
+\frametitle{Example Derivation}
 
 \begin{center}
 \bl{\begin{tabular}{lcl}
@@ -183,7 +185,6 @@
 \end{tabular}}
 \end{center}\bigskip
 
-
 \begin{center}
 \begin{tabular}{lcl}
 \bl{$S$} & \bl{$\rightarrow$} & \bl{$aSa$}\\
@@ -195,13 +196,12 @@
 \end{tabular}
 \end{center}
 
-\end{frame}}
+\end{frame}
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%   
 
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-\mode<presentation>{
 \begin{frame}[c]
-\frametitle{\begin{tabular}{c}Example Derivation\end{tabular}}
+\frametitle{Example Derivation}
 
 \begin{center}
 \bl{\begin{tabular}{lcl}
@@ -231,14 +231,12 @@
 \end{tabular}
 \end{center}
 
-\end{frame}}
+\end{frame}
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%   
 
-
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-\mode<presentation>{
 \begin{frame}[c]
-\frametitle{\begin{tabular}{c}Language of a CFG\end{tabular}}
+\frametitle{Language of a CFG}
 
 Let \bl{$G$} be a context-free grammar with start symbol \bl{$S$}. 
 Then the language \bl{$L(G)$} is:
@@ -254,13 +252,12 @@
 (but can also be strings).
 \end{itemize}
 
-\end{frame}}
+\end{frame}
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%   
 
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-\mode<presentation>{
 \begin{frame}[c]
-\frametitle{\begin{tabular}{c}Parse Trees\end{tabular}}
+\frametitle{Parse Trees}
 
 \begin{center}
 \bl{\begin{tabular}{lcl}
@@ -299,14 +296,12 @@
 \bl{\texttt{(2*3)+(3+4)}}
 \end{textblock}
 
-\end{frame}}
+\end{frame}
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%   
 
-
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-\mode<presentation>{
 \begin{frame}[c]
-\frametitle{\begin{tabular}{c}Arithmetic Expressions\end{tabular}}
+\frametitle{Arithmetic Expressions}
 
 \begin{center}
 \bl{\begin{tabular}{lcl}
@@ -321,16 +316,15 @@
 A CFG is \alert{left-recursive} if it has a nonterminal \bl{$E$} such
 that \bl{$E \rightarrow^+ E\cdot \ldots$}
 
-\end{frame}}
+\end{frame}
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%   
 
-
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-\mode<presentation>{
 \begin{frame}[c]
-\frametitle{\begin{tabular}{c}Ambiguous Grammars\end{tabular}}
+\frametitle{Ambiguous Grammars}
 
-A grammar is \alert{ambiguous} if there is a string that has at least two different parse trees.
+A grammar is \alert{ambiguous} if there is a string that has
+at least two different parse trees.
 
 
 \begin{center}
@@ -345,13 +339,12 @@
 
 \bl{\texttt{1 + 2 * 3 + 4}}
 
-\end{frame}}
+\end{frame}
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%   
 
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-\mode<presentation>{
 \begin{frame}[c]
-\frametitle{\begin{tabular}{c}Dangling Else\end{tabular}}
+\frametitle{Dangling Else}
 
 Another ambiguous grammar:\bigskip
 
@@ -365,13 +358,12 @@
 
 \bl{\texttt{if a then if x then y else c}}
 
-\end{frame}}
+\end{frame}
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 
 
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-\mode<presentation>{
 \begin{frame}[c]
-\frametitle{\begin{tabular}{c}Parser Combinators\end{tabular}}
+\frametitle{Parser Combinators}
 
 Parser combinators: \bigskip
 
@@ -383,30 +375,47 @@
 \end{minipage}\bigskip
 
 \begin{itemize}
+\item atomic parsers
 \item sequencing
 \item alternative
 \item semantic action
 \end{itemize}
 
-\end{frame}}
+\end{frame}
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%   
 
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-\mode<presentation>{
+\begin{frame}[c]
+
+Atomic parsers, for example, number tokens
+
+\begin{center}
+\bl{$\texttt{Num(123)}::rest \;\Rightarrow\; \{(\texttt{Num(123)}, rest)\}$} 
+\end{center}\bigskip
+
+\begin{itemize}
+\item you consume one or more token from the\\ 
+  input (stream)
+\item also works for characters and strings
+\end{itemize}
+\end{frame}
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%   
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 \begin{frame}[c]
 
 Alternative parser (code \bl{$p\;||\;q$})\bigskip
 
 \begin{itemize}
-\item apply \bl{$p$} and also \bl{$q$}; then combine the outputs
+\item apply \bl{$p$} and also \bl{$q$}; then combine 
+  the outputs
 \end{itemize}
 
 \begin{center}
 \large \bl{$p(\text{input}) \cup q(\text{input})$}
 \end{center}
 
-
-\end{frame}}
+\end{frame}
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%   
 
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@@ -418,7 +427,10 @@
 \begin{itemize}
 \item apply first \bl{$p$} producing a set of pairs
 \item then apply \bl{$q$} to the unparsed parts
-\item then combine the results:\\ \mbox{}\;\;((output$_1$, output$_2$), unparsed part)
+\item then combine the results:\medskip 
+\begin{center}
+((output$_1$, output$_2$), unparsed part)
+\end{center}
 \end{itemize}
 
 \begin{center}
@@ -517,78 +529,73 @@
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%  
 
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-\mode<presentation>{
 \begin{frame}[c]
-\frametitle{\begin{tabular}{c}Input Types of Parsers\end{tabular}}
+\frametitle{Input Types of Parsers}
 
 \begin{itemize}
-\item input: \alert{string}
-\item output: set of (output\_type, \alert{string})
+\item input: \alert{token list}
+\item output: set of (output\_type, \alert{token list})
 \end{itemize}\bigskip\pause
 
-actually it can be any input type as long as it is a kind of sequence
-(for example a string)
+actually it can be any input type as long as it is a kind of
+sequence (for example a string)
 
-\end{frame}}
+\end{frame}
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%  
 
 
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-\mode<presentation>{
 \begin{frame}[c]
-\frametitle{\begin{tabular}{c}Scannerless Parsers\end{tabular}}
+\frametitle{Scannerless Parsers}
 
 \begin{itemize}
 \item input: \alert{string}
 \item output: set of (output\_type, \alert{string})
 \end{itemize}\bigskip
 
-but lexers are better when whitespaces or comments need to be filtered out;
-then input is a sequence of tokens
+but lexers are better when whitespaces or comments need to be
+filtered out; then input is a sequence of tokens
 
-\end{frame}}
+\end{frame}
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%  
 
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-\mode<presentation>{
 \begin{frame}[c]
-\frametitle{\begin{tabular}{c}Successful Parses\end{tabular}}
+\frametitle{Successful Parses}
 
 \begin{itemize}
 \item input: string
 \item output: \alert{set of} (output\_type, string)
 \end{itemize}\bigskip
 
-a parse is successful whenever the input has been
-fully ``consumed'' (that is the second component is empty)
+a parse is successful whenever the input has been fully
+``consumed'' (that is the second component is empty)
 
-
-\end{frame}}
+\end{frame}
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%  
 
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-\mode<presentation>{
 \begin{frame}[c]
 \frametitle{Abstract Parser Class}
 
-\mbox{\lstset{language=Scala}\fontsize{10}{12}\selectfont
-\texttt{\lstinputlisting{../progs/app7.scala}}}
-\end{frame}}
+\small
+\lstinputlisting[language=Scala,xleftmargin=1mm]{../progs/app7.scala}
+\end{frame}
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%  
 
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-\mode<presentation>{
 \begin{frame}[c]
-{\lstset{language=Scala}\fontsize{10}{12}\selectfont
-\texttt{\lstinputlisting{../progs/app8.scala}}}
-\end{frame}}
+
+\small
+\fontsize{10}{12}\selectfont
+\lstinputlisting[language=Scala,xleftmargin=1mm]{../progs/app8.scala}
+\end{frame}
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 
 
 
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-\mode<presentation>{
 \begin{frame}[c]
-\frametitle{\begin{tabular}{c}Two Grammars\end{tabular}}
+\frametitle{Two Grammars}
 
 Which languages are recognised by the following two grammars?
 
@@ -606,83 +613,63 @@
 \end{tabular}}
 \end{center}
 
-\end{frame}}
+\end{frame}
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%   
 
-
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-\mode<presentation>{
 \begin{frame}[t]
-\frametitle{\begin{tabular}{c}Ambiguous Grammars\end{tabular}}
-
-\mbox{}\\[-25mm]\mbox{}
+\frametitle{Ambiguous Grammars}
 
 \begin{center}
-\begin{tikzpicture}[y=.2cm, x=.009cm]
- 	%axis
-	\draw (0,0) -- coordinate (x axis mid) (1000,0);
-    	\draw (0,0) -- coordinate (y axis mid) (0,30);
-    	%ticks
-    	\foreach \x in {0, 20, 100, 200,...,1000}
-     		\draw (\x,1pt) -- (\x,-3pt)
-			node[anchor=north] {\small \x};
-    	\foreach \y in {0,5,...,30}
-     		\draw (1pt,\y) -- (-3pt,\y) 
-     			node[anchor=east] {\small\y}; 
-	%labels      
-	\node[below=0.6cm] at (x axis mid) {\bl{1}s};
-	\node[rotate=90, left=1.2cm] at (y axis mid) {secs};
-
-	%plots
-	\draw[color=blue] plot[mark=*, mark options={fill=white}] 
-		file {s-grammar1.data};
-         \only<2->{\draw[color=red] plot[mark=triangle*, mark options={fill=white} ] 
-                  file {s-grammar2.data};}
-	%legend
-	\begin{scope}[shift={(400,20)}] 
-	\draw[color=blue] (0,0) -- 
-		plot[mark=*, mark options={fill=white}] (0.25,0) -- (0.5,0) 
-		node[right]{\small unambiguous};
-	\only<2->{\draw[yshift=\baselineskip, color=red] (0,0) -- 
-                plot[mark=triangle*, mark options={fill=white}] (0.25,0) -- (0.5,0)
-                node[right]{\small ambiguous};}  
-	\end{scope}
+\begin{tikzpicture}
+\begin{axis}[xlabel={\pcode{1}s},ylabel={time in secs},
+    enlargelimits=false,
+    xtick={0,100,...,1000},
+    xmax=1050,
+    ymax=33,
+    ytick={0,5,...,30},
+    scaled ticks=false,
+    axis lines=left,
+    width=11cm,
+    height=7cm, 
+    legend entries={unambiguous,ambiguous},  
+    legend pos=north east,
+    legend cell align=left,
+    x tick label style={font=\small,/pgf/number format/1000 sep={}}]
+\addplot[blue,mark=*, mark options={fill=white}] 
+  table {s-grammar1.data};
+\only<2>{
+  \addplot[red,mark=triangle*, mark options={fill=white}] 
+  table {s-grammar2.data};}  
+\end{axis}
 \end{tikzpicture}
 \end{center}
 
-\end{frame}}
+\end{frame}
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%   
 
-
-%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-\mode<presentation>{
-\begin{frame}[c]
-\frametitle{\begin{tabular}{c}While-Language\end{tabular}}
-
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%   
+\begin{frame}
+\frametitle{While-Language}
+\mbox{}\\[-23mm]\mbox{}
 
-\begin{center}
-\bl{\begin{tabular}{@{}lcl@{}}
-$Stmt$ & $\rightarrow$ &  $\text{skip}$\\
-              & $|$ & $Id := AExp$\\
-              & $|$ & $\text{if}\; B\!Exp \;\text{then}\; Block \;\text{else}\; Block$\\
-              & $|$ & $\text{while}\; B\!Exp \;\text{do}\; Block$\medskip\\
-$Stmts$ & $\rightarrow$ &  $Stmt \;\text{;}\; Stmts$\\
-              & $|$ & $Stmt$\medskip\\
-$Block$ & $\rightarrow$ &  $\{ Stmts \}$\\
-                & $|$ & $Stmt$\medskip\\
-$AExp$ & $\rightarrow$ & \ldots\\
-$BExp$ & $\rightarrow$ & \ldots\\
-\end{tabular}}
-\end{center}
+\bl{\begin{plstx}[rhs style=,one per line]
: \meta{Stmt} ::= skip
+         | \meta{Id} := \meta{AExp}
+         | if \meta{BExp} then \meta{Block} else \meta{Block}
+         | while \meta{BExp} do \meta{Block}\\
+: \meta{Stmts} ::= \meta{Stmt} ; \meta{Stmts}
+          | \meta{Stmt}\\
+: \meta{Block} ::= \{ \meta{Stmts} \}
+          | \meta{Stmt}\\
+: \meta{AExp} ::= \ldots\\
+: \meta{BExp} ::= \ldots\\
\end{plstx}}
 
-
-\end{frame}}
+\end{frame}
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%   
 
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
-\mode<presentation>{
 \begin{frame}[c]
-\frametitle{\begin{tabular}{c}An Interpreter\end{tabular}}
+\frametitle{An Interpreter}
 
 \begin{center}
 \bl{\begin{tabular}{l}
@@ -697,17 +684,13 @@
 
 \begin{itemize}
 \item the interpreter has to record the value of \bl{$x$} before assigning a value to \bl{$y$}\pause
-\item \bl{\text{eval}(stmt, env)}
+\item \bl{\texttt{eval(stmt, env)}}
 \end{itemize}
 
-
-\end{frame}}
+\end{frame}
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%   
 
 
-  
-
-
 \end{document}
 
 %%% Local Variables:  
diff -r c29853b672fb -r 19f23c4c2167 style.sty
--- a/style.sty	Sat Nov 01 16:19:05 2014 +0000
+++ b/style.sty	Sun Nov 02 09:10:15 2014 +0000
@@ -9,6 +9,7 @@
 \definecolor{darkblue}{rgb}{0,0,0.6}
 \usepackage[colorlinks=true,urlcolor=darkblue,linkcolor=darkblue]{hyperref}
 
+
 \newcommand\grid[1]{%
 \begin{tikzpicture}[baseline=(char.base)]
   \path[use as bounding box]