\documentclass[dvipsnames,14pt,t,xelatex]{beamer}
\usepackage{../slides}
\usepackage{../graphics}
\usepackage{../langs}
\usepackage{../data}

\hfuzz=220pt 

\newcommand{\bl}[1]{\textcolor{blue}{#1}}     

% beamer stuff 
\renewcommand{\slidecaption}{AFL 01, King's College London}


\begin{document}

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\begin{frame}[t]
\frametitle{%
  \begin{tabular}{@ {}c@ {}}
  \\[-3mm]
  \LARGE Automata and \\[-2mm] 
  \LARGE Formal Languages (1)\\[-3mm] 
  \end{tabular}}

  \begin{center}
  \includegraphics[scale=0.3]{pics/ante1.jpg}\hspace{5mm}
  \includegraphics[scale=0.31]{pics/ante2.jpg}\\
  \footnotesize\textcolor{gray}{Antikythera automaton, 100 BC (Archimedes?)}
  \end{center}

\normalsize
  \begin{center}
  \begin{tabular}{ll}
  Email:  & christian.urban at kcl.ac.uk\\
  Office: & S1.27 (1st floor Strand Building)\\
  Slides: & KEATS
  \end{tabular}
  \end{center}


\end{frame}
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\begin{frame}[c]

\begin{textblock}{1}(2,5)
\begin{tabular}{c}
\includegraphics[scale=0.15]{pics/servers.png}\\[-2mm]
\small Server
\end{tabular}
\end{textblock}

\begin{textblock}{1}(5.6,4)
  \begin{tikzpicture}[scale=1.1]
  \draw[white] (0,1) node (X) {};
  \draw[white] (2,1) node (Y) {};
   \draw[white] (0,0) node (X1) {};
  \draw[white] (2,0) node (Y1) {};
   \draw[white] (0,-1) node (X2) {};
  \draw[white] (2,-1) node (Y2) {};
  \draw[red, <-, line width = 2mm] (X) -- (Y);
  \node [inner sep=5pt,label=above:\textcolor{black}{GET request}] at ($ (X)!.5!(Y) $) {};
  \draw[red, ->, line width = 2mm] (X1) -- (Y1);
  \node [inner sep=5pt,label=above:\textcolor{black}{webpage}] at ($ (X1)!.5!(Y1) $) {};
  \draw[red, <-, line width = 2mm] (X2) -- (Y2);
  \node [inner sep=7pt,label=above:\textcolor{black}{POST data}] at ($ (X2)!.5!(Y2) $) {};
  \end{tikzpicture}
\end{textblock}


\begin{textblock}{1}(9,5.5)
\begin{tabular}{c}
\includegraphics[scale=0.15]{pics/laptop.png}\\[-2mm]
\small Browser
\end{tabular}
\end{textblock}
  
\only<2>{  
\begin{textblock}{10}(2,13.5)
\begin{itemize}
\item programming languages, compilers
\end{itemize}
\end{textblock}}
  
\end{frame}
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\begin{frame}[c]

transforming strings into structured data\\[10mm]

{\LARGE\bf Lexing}\medskip\\
\hspace{5mm}(recognising ``words'')\\[6mm]

{\LARGE\bf Parsing}\medskip\\
\hspace{5mm}(recognising ``sentences'')

\end{frame}
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\begin{frame}[c]

The subject is quite old:

\begin{itemize}
\item Turing Machines, 1936
\item first compiler for COBOL, 1957 (Grace Hopper)
\item but surprisingly research papers are still published now
\end{itemize}

\begin{flushright}
\includegraphics[scale=0.3]{pics/hopper.jpg}\\
\footnotesize\textcolor{gray}{Grace Hopper}
\end{flushright}

{\footnotesize\textcolor{gray}{(she made it to David Letterman's Tonight Show, \url{http://www.youtube.com/watch?v=aZOxtURhfEU})}}

\end{frame}
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\mode<presentation>{
\begin{frame}[c]
\frametitle{\begin{tabular}{c}This Course\end{tabular}}

\begin{itemize}
\item the ultimate goal is to implement a small compiler (a really small one for the JVM)\bigskip
\end{itemize}

Let's start with:

\begin{itemize}
\item a web-crawler
\item an email harvester
\item a web-scraper
\end{itemize}

\begin{textblock}{6}(10,7)
\begin{tikzpicture}[scale=0.38]
\begin{axis}[axis x line=bottom, axis y line=left, ylabel=secs,
    xlabel=n,
    enlargelimits=0.05,
    ybar interval=0.7, legend style=small]
\addplot file {interpreted2.data};
\addplot file {compiled2.data};
%\legend{interpreted, compiled}
\end{axis}
\end{tikzpicture}
\end{textblock}


\end{frame}}
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\begin{frame}[t]
\frametitle{A Web-Crawler}

\mbox{}\\[10mm]

\begin{enumerate}
\item given an URL, read the corresponding webpage
\item extract all links from it
\item call the web-crawler again for all these links
\end{enumerate}

\end{frame}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%   

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\mode<presentation>{
\begin{frame}[t]
\frametitle{A Web-Crawler}

\mbox{}\\[10mm]


\begin{enumerate}
\item given an URL, read the corresponding webpage
\item if not possible print, out a problem
\item if possible, extract all links from it
\item call the web-crawler again for all these links
\end{enumerate}\bigskip\pause

\small (we need a bound for the number of recursive calls)

\small (the purpose is to check all links on my own webpage)
\end{frame}}
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\begin{frame}[c]
\frametitle{Scala}

\small a simple Scala function for reading webpages

\footnotesize
\lstinputlisting{../progs/app0.scala}\pause
\lstinline{get_page("""http://www.inf.kcl.ac.uk/staff/urbanc/""")}\pause\bigskip


\small slightly more complicated for handling errors properly:

\footnotesize
\lstinputlisting{../progs/app1.scala}


\end{frame}
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\begin{frame}[c]
\frametitle{Why Scala?}

\begin{textblock}{6}(1,3)
\begin{tabular}{l}
\mbox{}\hspace{-1mm}\includegraphics[scale=0.36]{pics/twitter.png}\\[-1mm]
\includegraphics[scale=0.30]{pics/linked.png}\\
\includegraphics[scale=0.30]{pics/guardian.jpg}\\[-3mm]
\mbox{}\hspace{-2mm}\includegraphics[scale=0.38]{pics/morgan.png}\\[-3mm]
\includegraphics[scale=0.30]{pics/suisse.png}\\
\includegraphics[scale=0.20]{pics/edf.png}\\[-1mm]
\includegraphics[scale=0.08]{pics/novell.png}\\[-1mm]
\includegraphics[scale=0.30]{pics/foursquare.png}\\
\includegraphics[scale=0.30]{pics/hsbc.png}\\
{\large\bf ...}
\end{tabular}
\end{textblock}
 
\only<2->{  
\begin{textblock}{6}(6,3)
\includegraphics[scale=0.35]{pics/jobgraph.png}\\
\end{textblock}}  
  
\only<3->{  
\begin{textblock}{6}(7.3,9.2)
\begin{tabular}{l}
\footnotesize 2013: 1$\%$\\[-2mm]
\footnotesize 2014: 3$\%$\\[-2mm]
\footnotesize 2015: 9$\%$\\[-2mm]
\footnotesize 2016: 27$\%$\\[-2mm]
\footnotesize 2017: 81$\%$\\[-2mm]
\footnotesize 2018: 243$\%$ \raisebox{-1mm}{\includegraphics[scale=0.02]{pics/smiley.jpg}}
\end{tabular}
\end{textblock}} 
  
\only<3->{  
\begin{textblock}{6}(6,9.5)
\footnotesize 5 yrs $\begin{cases}\mbox{}\\[1.4cm]\end{cases}$
\end{textblock}}

\only<4->{  
\begin{textblock}{11}(5,14.1)
\textcolor{gray}{
\footnotesize {\bf in London today:} 1 Scala job for every 30 Java jobs;\\[-2mm]
Scala programmers seem to get up to 20\% better salary}
\end{textblock}}


\only<5->{
\begin{textblock}{1}(3,6)
\begin{bubble}[8.5cm]
\normalsize
Scala is a functional and object-oriented programming
language; compiles to the JVM; does not need null-pointer
exceptions; a course on Coursera\\
\mbox{}\hfill\url{http://www.scala-lang.org}
\end{bubble}
\end{textblock}}

\end{frame}
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\begin{frame}[t]
\frametitle{A Regular Expression}

\begin{itemize}
\item \ldots{} is a pattern or template for specifying strings
\end{itemize}\bigskip
  
\begin{center}  
\only<1>{\code{"https?://[^\"]*"}}%
\only<2>{\code{""""https?://[^\"]*"""".r}}
\end{center}\bigskip\bigskip

matches for example\\  
\code{"http://www.foobar.com"}\\
\code{"https://www.tls.org"}\\

\end{frame}
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\begin{frame}[c]

\code{rexp.findAllIn(string)}\medskip
  
returns a list of all (sub)strings that match the 
regular expression\bigskip\bigskip  
  
\code{rexp.findFirstIn(string)}\medskip
  
returns either \code{None} if no (sub)string matches 
or \code{Some(s)} with the first (sub)string
  
\end{frame}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%   

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\begin{frame}[c]

\footnotesize
\lstinputlisting{../progs/app2.scala}\medskip

\code{crawl(some_start_URL, 2)}\

\end{frame}
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\begin{frame}[c]

\footnotesize
a version that only ``crawls'' links in my domain:

\lstinputlisting{../progs/app3.scala}

\end{frame}
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\begin{frame}[c]

\footnotesize
a little email ``harvester'':

\footnotesize
\lstinputlisting{../progs/app4.scala}\bigskip

\tiny
\url{http://net.tutsplus.com/tutorials/other/8-regular-expressions-you-should-know/}

\end{frame}
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\begin{frame}[t]
\frametitle{\begin{tabular}{c}Regular Expressions\end{tabular}}

Their inductive definition:\medskip

\begin{textblock}{6}(2,5)
  \begin{tabular}{@ {}rrl@ {\hspace{13mm}}l}
  \bl{r} & \bl{$::=$}  & \bl{$\varnothing$}  & null\\
         & \bl{$\mid$} & \bl{$\epsilon$}        & empty string / "" / []\\
         & \bl{$\mid$} & \bl{c}                         & character\\
         & \bl{$\mid$} & \bl{r$_1$ $\cdot$ r$_2$} & sequence\\
         & \bl{$\mid$} & \bl{r$_1$ + r$_2$}  & alternative / choice\\
         & \bl{$\mid$} & \bl{r$^*$}                   & star (zero or more)\\
  \end{tabular}
  \end{textblock}
  
\end{frame}}
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\begin{frame}[t]
\frametitle{Regular Expressions}

\small
In Scala:

\footnotesize
\lstinputlisting{../progs/app51.scala}

  
\end{frame}
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\mode<presentation>{
\begin{frame}[c]
\frametitle{\begin{tabular}{c}The Meaning of a\\[-2mm] 
  Regular Expression\end{tabular}}

\begin{textblock}{15}(1,4)
 \begin{tabular}{@ {}rcl}
 \bl{$L$($\varnothing$)}  & \bl{$\dn$} & \bl{$\varnothing$}\\
 \bl{$L$($\epsilon$)}        & \bl{$\dn$} & \bl{$\{$""$\}$}\\
 \bl{$L$(c)}                         & \bl{$\dn$} & \bl{$\{$"c"$\}$}\\
 \bl{$L$(r$_1$ + r$_2$)} & \bl{$\dn$} & \bl{$L$(r$_1$) $\cup$ $L$(r$_2$)}\\
 \bl{$L$(r$_1$ $\cdot$ r$_2$)}  & \bl{$\dn$} & \bl{$\{$ s$_1$ @ s$_2$ $|$ s$_1$ $\in$ $L$(r$_1$) $\wedge$ s$_2$ $\in$ 
     $L$(r$_2$) $\}$}\\
 \bl{$L$(r$^*$)}                   & \bl{$\dn$} & \onslide<4->{\bl{$\bigcup_{n \ge 0}$ $L$(r)$^n$}}\\
  \end{tabular}\bigskip
  
\onslide<2->{
\hspace{5mm}\bl{$L$(r)$^0$ $\;\dn\;$ $\{$""$\}$}\\
\bl{$L$(r)$^{n+1}$ $\;\dn\;$ $L$(r) @ $L$(r)$^n$}\hspace{9mm}\onslide<3->{\small\textcolor{gray}{(append on sets)}\\
\small\hspace{5cm}\textcolor{gray}{$\{$ s$_1$ @ s$_2$ $|$ s$_1$ $\in$ $L$(r) $\wedge$ s$_2$ $\in$ 
     $L$(r)$^n$ $\}$}}
}  
    \end{textblock}

\end{frame}}
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\mode<presentation>{
\begin{frame}[c]
\frametitle{\begin{tabular}{c}The Meaning of Matching\end{tabular}}

\large
a regular expression \bl{r} matches a string \bl{s} is defined as

\begin{center}
\bl{s $\in$ $L$(r)}\\ 
\end{center}

\end{frame}}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%   

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\mode<presentation>{
\begin{frame}[c]
\frametitle{\begin{tabular}{c}This Course\end{tabular}}

We will have a look at:

\begin{itemize}
\item regular expressions / regular expression matching
\item derivatives 
\item automata
\item parsing
\item grammars
\item a small interpreter / compiler
\end{itemize}

\end{frame}}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%   



%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\begin{frame}[c]
\frametitle{Written Exam}

\begin{itemize}
\item Accounts for 75\%.\bigskip

\item You will understand the question ``Is this relevant for
      the exam?'' is very demotivating for the lecturer!\bigskip\\

\item Deal: Whatever is in the homework (and is not marked
      ``optional'') is relevant for the exam.
\end{itemize}

\end{frame}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%   

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\begin{frame}[t]
\frametitle{Coursework}

\begin{itemize}
\item Accounts for 25\%. Two strands. Choose \alert{\bf one}!\bigskip
\end{itemize}

\begin{columns}[t]
\begin{column}{.5\textwidth}
\underline{\bf Strand 1}\medskip
\begin{itemize}
\item four programming subtasks:
\begin{itemize}
\item matcher (5\%, 13.10.) 
\item lexer (5\%, 03.11.)
\item parser (5\%, 27.11.)
\item compiler (10\%, 12.12.)
\end{itemize}
\end{itemize}
\end{column}

\hspace{-45pt}\vrule{}\hspace{10pt}

\begin{column}{.5\textwidth}
\underline{\bf Strand 2}\smallskip
\begin{itemize}
\item one task: prove the correctness of a regular expression matcher in 
the Isabelle theorem prover
\item 25\%, submission 12.12.
\end{itemize}
\end{column}
\end{columns}\medskip

\small
\begin{itemize}
\item Solving more than one strand will {\bf not} give you more 
marks.\\[-2mm]
\item The exam will contain in much, much smaller form 
elements from both (but will also be in lectures and HW).
\end{itemize}

\end{frame}
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\end{document}

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