\documentclass[dvipsnames,14pt,t,xelatex]{beamer}+
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\usepackage{../slides}+
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\usepackage{../graphics}+
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\usepackage{../langs}+
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%%\usepackage{../data}+
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\usepackage[export]{adjustbox}+
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\hfuzz=220pt +
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+
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%\setmonofont[Scale=.88]{Consolas}+
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%\newfontfamily{\consolas}{Consolas}+
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+
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\lstset{language=Scala,+
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        style=mystyle,+
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        numbersep=0pt,+
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        numbers=none,+
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        xleftmargin=0mm}+
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+
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\newcommand{\bl}[1]{\textcolor{blue}{#1}}     +
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+
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% beamer stuff +
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\renewcommand{\slidecaption}{PEP (Scala) 05, King's College London}+
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+
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\begin{filecontents}{re3a.data}+
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1500001 0.88485+
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2500001 1.68619+
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3000001 1.94957+
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3500001 2.15878+
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4000001 2.59918+
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4500001 5.90679+
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5000001 13.11295+
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5500001 19.15376+
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6000001 40.16373+
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\end{filecontents}+
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\begin{filecontents}{re-python2.data}+
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1 0.033+
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5 0.036+
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10 0.034+
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15 0.036+
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18 0.059+
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19 0.084+
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20 0.141+
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21 0.248+
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22 0.485+
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23 0.878+
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24 1.71+
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25 3.40+
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26 7.08+
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27 14.12+
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28 26.69+
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\end{filecontents}+
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+
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\begin{filecontents}{re-java.data}+
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5  0.00298+
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10  0.00418+
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15  0.00996+
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16  0.01710+
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17  0.03492+
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18  0.03303+
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23  0.82234+
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24  1.70251+
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26  6.63998+
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27  13.35120+
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28  29.81185+
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\end{filecontents}+
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+
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%All O2 technical teams are working closely with one of our third party suppliers who has identified a global software issue in their system which has impacted data services.  +
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+
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+
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\begin{document}+
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%+
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\begin{frame}[t]+
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\frametitle{%+
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  \begin{tabular}{@ {}c@ {}}+
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  \\[5mm]+
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  \huge PEP Scala (5) +
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  \end{tabular}}+
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+
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  \normalsize+
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  \begin{center}+
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  \begin{tabular}{ll}+
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    Email:  & christian.urban at kcl.ac.uk\\+
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    Office: & N\liningnums{7.07} (North Wing, Bush House)\\+
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    Slides \& Code: & KEATS\medskip\\+
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    Office Hours: &  Mondays 12:00 -- 14:00\\+
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  \end{tabular}+
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  \end{center}+
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+
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+
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\end{frame}+
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%     +
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+
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%     +
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+
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\begin{frame}[c]+
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\frametitle{Marks for CW7 (Part 1 +  2)}+
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+
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Raw marks (234 submissions):+
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+
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\begin{itemize}+
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\item 6\%: \hspace{4mm}192 students+
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\item 5\%: \hspace{4mm}16+
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\item 4\%: \hspace{4mm}7+
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\item 3\%: \hspace{4mm}2+
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\item 2\%: \hspace{4mm}6+
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\item 1\%: \hspace{4mm}1+
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\item 0\%: \hspace{4mm}9 +
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\end{itemize}  +
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\end{frame}+
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+
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+
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%+
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+
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+
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+
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%+
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\begin{frame}[c,fragile]+
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\small+
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  +
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\begin{lstlisting}[language=Scala, numbers=none, xleftmargin=-7mm]+
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def get_csv_url(url: String) : List[String] = {+
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  val csv = Try(Source.fromURL(url)).getOrElse(null)+
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   if (csv == null){+
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     List()+
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   }+
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   else {+
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     ....+
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   }+
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}+
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\end{lstlisting}+
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+
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\pause+
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\bigskip+
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\rule{11cm}{0.3mm}+
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\bigskip+
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+
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\begin{lstlisting}[language=Scala, numbers=none, xleftmargin=-7mm]+
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def get_csv_url(url: String) : List[String] = {+
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  Try(Source.fromURL(url)....).getOrElse(Nil)+
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\end{lstlisting}+
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+
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+
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\end{frame}+
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% +
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+
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+
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+
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+
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%+
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\begin{frame}[c,fragile]+
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\small+
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  +
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\begin{lstlisting}[language=Scala, numbers=none, xleftmargin=-7mm]+
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def get_csv_url(url: String) : List[String] = {+
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    try {+
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        val csvFile = Source.fromURL(url)+
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        ....+
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    } catch {+
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        case unknown : Throwable => List()+
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    }+
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}+
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\end{lstlisting}+
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+
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+
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\bigskip+
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\rule{11cm}{0.3mm}+
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\bigskip+
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+
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\begin{lstlisting}[language=Scala, numbers=none, xleftmargin=-7mm]+
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def get_csv_url(url: String) : List[String] = {+
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  Try(Source.fromURL(url)....).getOrElse(Nil)+
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\end{lstlisting}+
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+
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+
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\end{frame}+
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% +
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+
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%+
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  \begin{frame}[c]+
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  \frametitle{Dijkstra on Testing}+
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  +
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  \begin{bubble}[10cm]+
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  ``Program testing can be a very effective way to show the+
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  presence of bugs, but it is hopelessly inadequate for showing+
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  their absence.''+
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  \end{bubble}\bigskip+
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  +
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  +
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  \end{frame}+
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%+
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+
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%+
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\begin{frame}[c]+
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\frametitle{\Large Proving Programs to be Correct}+
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+
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\begin{bubble}[10cm]+
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\small+
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{\bf Theorem:} There are infinitely many prime +
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numbers.\medskip\\+
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+
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{\bf Proof} \ldots\\+
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\end{bubble}\bigskip+
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+
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+
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similarly\bigskip+
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+
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\begin{bubble}[10cm]+
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\small+
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{\bf Theorem:} The program is doing what +
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it is supposed to be doing.\medskip+
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+
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{\bf Long, long proof} \ldots\\+
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\end{bubble}\bigskip\medskip+
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+
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\small This can be a gigantic proof. The only hope is to have+
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help from the computer. `Program' is here to be understood to be+
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quite general (compiler, OS, \ldots).+
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+
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\end{frame}+
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%+
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+
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%     +
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+
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\begin{frame}[c]+
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\frametitle{Can This Be Done?}+
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+
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\begin{itemize}+
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\item in 2011, verification of a small C-compiler (CompCert)+
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\begin{itemize}+
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\item ``if my input program has a certain behaviour, then the compiled machine code has the same behaviour''+
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\item is as good as \texttt{gcc -O1}, but much, much less buggy +
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\end{itemize}+
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\end{itemize}+
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+
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\begin{center}+
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  \includegraphics[scale=0.12]{../pics/compcert.png}+
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\end{center}+
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+
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\end{frame}+
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%+
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+
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+
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+
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%     +
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\begin{frame}[c]+
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\frametitle{Fuzzy Testing C-Compilers}+
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+
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\begin{itemize}+
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\item tested GCC, LLVM and others by randomly generating +
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C-programs+
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\item found more than 300 bugs in GCC and also+
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many in LLVM (some of them highest-level critical)\bigskip+
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\item about CompCert:+
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+
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\begin{bubble}[10cm]\small ``The striking thing about our CompCert+
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results is that the middle-end bugs we found in all other+
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compilers are absent. As of early 2011, the under-development+
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version of CompCert is the only compiler we have tested for+
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which Csmith cannot find wrong-code errors. This is not for+
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lack of trying: we have devoted about six CPU-years to the+
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task.'' +
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\end{bubble} +
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\end{itemize}+
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+
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\end{frame}+
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%     +
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+
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%+
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\begin{frame}[c]+
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\frametitle{seL4 / Isabelle}+
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+
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\begin{itemize}+
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\item verified a microkernel operating system ($\approx$8000 lines of C code)\bigskip+
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\item US DoD has competitions to hack into drones; they found that the+
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  isolation guarantees of seL4 hold up\bigskip+
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\item CompCert and seL4 sell their code  +
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\end{itemize}+
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+
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\only<2>{+
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\begin{textblock}{5}(5.5,1.9)+
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  \includegraphics[scale=0.25]{../pics/drone.jpg}+
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\end{textblock}}+
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+
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\end{frame}+
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%+
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+
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+
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%  +
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\begin{frame}[c]+
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  \frametitle{CW9 : Regexes}+
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  +
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\begin{center}+
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  Graphs: $(a^*)^* b$ and strings $\underbrace{\;a\ldots a\;}_{n}$\bigskip+
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  +
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\begin{tabular}[t]{@{\hspace{-8mm}}c@{\hspace{-4mm}}c@{}}+
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\raisebox{6mm}{\begin{tikzpicture}+
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\begin{axis}[+
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    xlabel={$n$},+
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    x label style={at={(1.05,0.0)}},+
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    ylabel={time in secs},+
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    enlargelimits=false,+
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    xtick={0,5,...,30},+
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    xmax=33,+
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    ymax=35,+
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    ytick={0,5,...,30},+
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    scaled ticks=false,+
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    axis lines=left,+
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    width=5.5cm,+
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    height=5cm, +
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    legend entries={Python,  Java 8},  +
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    legend pos=north west,+
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    legend cell align=left]+
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\addplot[blue,mark=*, mark options={fill=white}] table {re-python2.data};  +
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\addplot[cyan,mark=*, mark options={fill=white}] table {re-java.data};+
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\end{axis}+
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\end{tikzpicture}}+
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  &+
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\onslide<1>{\begin{tikzpicture}+
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  \begin{axis}[+
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    xlabel={$n$},+
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    x label style={at={(1.05,0.0)}},+
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    ylabel={time in secs},+
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    enlargelimits=false,+
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    ymax=35,+
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    ytick={0,5,...,30},+
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    axis lines=left,+
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    %%scaled ticks=false,+
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    width=5.5cm, +
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    height=5cm]+
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%%\addplot[green,mark=square*,mark options={fill=white}] table {re2a.data};    +
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\addplot[red,mark=square*,mark options={fill=white}] table {re3a.data};+
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\end{axis}+
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\end{tikzpicture}}+
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\end{tabular}+
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\end{center}+
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+
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+
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\small+
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\hfill Kuklewicz: most POSIX matchers are buggy\\+
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\footnotesize+
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\hfill \url{http://www.haskell.org/haskellwiki/Regex_Posix}+
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\end{frame}+
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%     +
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+
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\begin{frame}[c]+
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\frametitle{Where to go on from here?}+
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+
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\begin{itemize}+
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\item Martin Odersky (EPFL)\ldots he is currently throwing out everything+
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  and starts again with the dotty compiler for Scala\medskip+
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+
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\item Elm (\url{http://elm-lang.org})\ldots web applications with style\medskip   +
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+
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\item Haskell, Ocaml, Standard ML, Scheme, \ldots +
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\end{itemize}  +
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\end{frame}+
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+
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+
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%+
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+
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%+
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\begin{frame}[c,fragile]+
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\frametitle{\alert{Questions?}}+
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+
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{\tiny+
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\begin{verbatim}+
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                               *+
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                              * *+
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                             *   *+
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                            * * * *+
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                           *       *+
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                          * *     * *+
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                         *   *   *   *+
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                        * * * * * * * *+
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                       *               *+
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                      * *             * *+
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                     *   *           *   *+
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                    * * * *         * * * *+
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                   *       *       *       *+
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                  * *     * *     * *     * *+
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                 *   *   *   *   *   *   *   *+
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                * * * * * * * * * * * * * * * *+
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               *                               *+
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              * *                             * *+
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             *   *                           *   *+
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            * * * *                         * * * *+
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           *       *                       *       *+
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          * *     * *                     * *     * *+
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         *   *   *   *                   *   *   *   *+
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        * * * * * * * *                 * * * * * * * *+
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       *               *               *               *+
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      * *             * *             * *             * *+
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     *   *           *   *           *   *           *   *+
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    * * * *         * * * *         * * * *         * * * *+
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   *       *       *       *       *       *       *       *+
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  * *     * *     * *     * *     * *     * *     * *     * *+
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 *   *   *   *   *   *   *   *   *   *   *   *   *   *   *   *+
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* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *+
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\end{verbatim}}+
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+
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+
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\begin{textblock}{6}(8.5,3.5)+
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\begin{bubble}[5cm]+
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\footnotesize+
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\begin{lstlisting}[language=Scala, numbers=none, xleftmargin=-1mm]+
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++++++++[>+>++++<<-]>++>>+
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+<[-[>>+<<-]+>>]>+[-<<<[-+
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>[+[-]+>++>>>-<<]<[<]>>+++
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++++[<<+++++>>-]+<<++.[-]+
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<<]>.>+[>>]>+]+
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\end{lstlisting}+
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\end{bubble}+
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\end{textblock}+
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  +
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\end{frame}+
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%   +
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+
−
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%     +
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+
−
\begin{frame}[c]+
−
\frametitle{Marks for CW6 (Part 1 + 2)}+
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+
−
Raw marks:+
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+
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\begin{itemize}+
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\item 6\%: 154 students+
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\item 5\%: 66+
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\item 4\%: 18+
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\item 3\%: 13+
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\item 2\%: 2+
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\item 1\%: 1+
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\item 0\%: 21 +
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\end{itemize}  +
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\end{frame}+
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+
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+
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%+
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+
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\end{document}+
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+
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+
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\end{document}+
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+
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%%% Local Variables:  +
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%%% mode: latex+
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%%% TeX-master: t+
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%%% End: +
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+
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