\documentclass[dvipsnames,14pt,t]{beamer}\usepackage{beamerthemeplainculight}\usepackage[T1]{fontenc}\usepackage[latin1]{inputenc}\usepackage{mathpartir}\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}\usepackage{graphicx} \definecolor{javared}{rgb}{0.6,0,0} % for strings\definecolor{javagreen}{rgb}{0.25,0.5,0.35} % comments\definecolor{javapurple}{rgb}{0.5,0,0.35} % keywords\definecolor{javadocblue}{rgb}{0.25,0.35,0.75} % javadoc\lstset{language=Java, basicstyle=\ttfamily, keywordstyle=\color{javapurple}\bfseries, stringstyle=\color{javagreen}, commentstyle=\color{javagreen}, morecomment=[s][\color{javadocblue}]{/**}{*/}, numbers=left, numberstyle=\tiny\color{black}, stepnumber=1, numbersep=10pt, tabsize=2, showspaces=false, showstringspaces=false}\lstdefinelanguage{scala}{ morekeywords={abstract,case,catch,class,def,% do,else,extends,false,final,finally,% for,if,implicit,import,match,mixin,% new,null,object,override,package,% private,protected,requires,return,sealed,% super,this,throw,trait,true,try,% type,val,var,while,with,yield}, otherkeywords={=>,<-,<\%,<:,>:,\#,@}, sensitive=true, morecomment=[l]{//}, morecomment=[n]{/*}{*/}, morestring=[b]", morestring=[b]', morestring=[b]"""}\lstset{language=Scala, basicstyle=\ttfamily, keywordstyle=\color{javapurple}\bfseries, stringstyle=\color{javagreen}, commentstyle=\color{javagreen}, morecomment=[s][\color{javadocblue}]{/**}{*/}, numbers=left, numberstyle=\tiny\color{black}, stepnumber=1, numbersep=10pt, tabsize=2, showspaces=false, showstringspaces=false}% beamer stuff \renewcommand{\slidecaption}{AFL 01, King's College London, 26.~September 2012}\begin{document}%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%\mode<presentation>{\begin{frame}<1>[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\\ Of$\!$fice: & S1.27 (1st floor Strand Building)\\ Slides: & KEATS \end{tabular} \end{center}\end{frame}} %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%\mode<presentation>{\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}}%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%\mode<presentation>{\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}}%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%\mode<presentation>{\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}}%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%\mode<presentation>{\begin{frame}[c]\frametitle{\begin{tabular}{c}This Course\end{tabular}}\begin{itemize}\item the ultimate goal is to implement a small web-browser (really small one)\bigskip\end{itemize}Let's start with:\begin{itemize}\item a web-crawler\item an email harvester\item a web-scraper\end{itemize}\end{frame}}%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%\mode<presentation>{\begin{frame}[t]\frametitle{\begin{tabular}{c}A Web-Crawler\end{tabular}}\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}}%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%\mode<presentation>{\begin{frame}[t]\frametitle{\begin{tabular}{c}A Web-Crawler\end{tabular}}\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}}%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%\mode<presentation>{\begin{frame}[c]\frametitle{\begin{tabular}{c}Scala\end{tabular}}\footnotesize a simple Scala function for reading webpages\\[-3mm]{\lstset{language=Scala}\fontsize{8}{10}\selectfont\texttt{\lstinputlisting{app0.scala}}}\pause{\lstset{language=Scala}\fontsize{8}{10}\selectfont\texttt{\lstinline{get_page("""http://www.inf.kcl.ac.uk/staff/urbanc/""")}}}\pause\bigskip\footnotesize slightly more complicated for handling errors properly:\\[-3mm]\footnotesize{\lstset{language=Scala}\fontsize{8}{10}\selectfont\texttt{\lstinputlisting{app1.scala}}}\end{frame}}%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%\mode<presentation>{\begin{frame}[t]\frametitle{\begin{tabular}{c}A Regular Expression\end{tabular}}\begin{itemize}\item \ldots{} is a pattern or template for specifying strings\end{itemize}\bigskip\begin{center} \only<1>{{\lstset{language=Scala}\fontsize{18}{19}\selectfont\bf\texttt{"https?://[$\hat{\hspace{2mm}}$"]*"}}}%\only<2>{{\lstset{language=Scala}\fontsize{18}{19}\selectfont\bf\texttt{"""\textbackslash{}"https?://[$\hat{\hspace{2mm}}$\textbackslash{}"]*\textbackslash{}"""".r}}}\end{center}\bigskip\bigskipmatches for example\\ \;{\lstset{language=Scala}\fontsize{12}{14}\selectfont\bf\texttt{"http://www.foobar.com"}}\\\;{\lstset{language=Scala}\fontsize{12}{14}\selectfont\bf\texttt{"https://www.tls.org"}}\\\end{frame}}%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%\mode<presentation>{\begin{frame}[c]{\lstset{language=Scala}\fontsize{18}{19}\selectfont\bf\texttt{rexp.findAllIn(string)}}\medskipreturns a list of all (sub)strings that match the regular expression\bigskip\bigskip {\lstset{language=Scala}\fontsize{18}{19}\selectfont\bf\texttt{rexp.findFirstIn(string)}}\medskipreturns either {\bf\texttt{None}} if no (sub)string matches or {\bf\texttt{Some(s)}} with the first (sub)string\end{frame}}%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%\mode<presentation>{\begin{frame}[c]{\lstset{language=Scala}\fontsize{8}{10}\selectfont\texttt{\lstinputlisting{app2.scala}}}\medskip{\lstset{language=Scala}\fontsize{8}{10}\selectfont\texttt{crawl(some\_start\_URL, 2)}}\\end{frame}}%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%\mode<presentation>{\begin{frame}[c]\footnotesizea version that only ``crawls'' links in my domain:{\lstset{language=Scala}\fontsize{8}{10}\selectfont\texttt{\lstinputlisting{app3.scala}}}\end{frame}}%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%\mode<presentation>{\begin{frame}[c]\footnotesizea little email ``harvester'':{\lstset{language=Scala}\fontsize{8}{10}\selectfont\texttt{\lstinputlisting{app4.scala}}}\bigskip\tiny\textcolor{gray}{\url{http://net.tutsplus.com/tutorials/other/8-regular-expressions-you-should-know/}}\end{frame}}%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% \newcommand{\bl}[1]{\textcolor{blue}{#1}} %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%\mode<presentation>{\begin{frame}[c]\frametitle{\begin{tabular}{c}Regular Expressions\end{tabular}}\begin{textblock}{6}(2,4) \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}}%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%\mode<presentation>{\begin{frame}[t]\frametitle{\begin{tabular}{c}Regular Expressions\end{tabular}}{\lstset{language=Scala}\fontsize{8}{10}\selectfont\texttt{\lstinputlisting{app51.scala}}}\end{frame}}%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% \newcommand{\dn}{\stackrel{\mbox{\scriptsize def}}{=}}% for definitions%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%\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}}%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%\mode<presentation>{\begin{frame}[c]\frametitle{\begin{tabular}{c}The Meaning of Matching\end{tabular}}\largea 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 automata\item the Myhill-Nerode theorem\item parsing\item grammars\item a small interpreter / web browser\end{itemize}\end{frame}}%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%\mode<presentation>{\begin{frame}[c]\frametitle{\begin{tabular}{c}Exam\end{tabular}}\begin{itemize}\item The question ``Is this relevant for the exam?'' is not appreciated!\bigskip\\Whatever is in the homework sheets (and is not marked optional) is relevant for theexam.\\ No code needs to be written.\end{itemize}\end{frame}}%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% \end{document}%%% Local Variables: %%% mode: latex%%% TeX-master: t%%% End: