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

% beamer stuff 
\renewcommand{\slidecaption}{CFL, King's College London}
\newcommand{\bl}[1]{\textcolor{blue}{#1}}       


\begin{document}

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

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

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

\Large\bf There are more problems, than there are
programs.\bigskip\bigskip\pause\\

There must be a problem for which there is no program.
\end{frame}
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\begin{frame}[c]
\frametitle{Subsets}

\Large
If \bl{$A \subseteq B$} then \bl{$A$} has fewer elements
than \bl{$B$}\bigskip\bigskip

\Large
\bl{$A \subseteq B$} and \bl{$B \subseteq A$}\bigskip

then \bl{$A = B$}
\end{frame}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%   


%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
  \begin{frame}[c]
  
  \begin{center}
  \begin{tikzpicture}
  
  \draw (-4,2.5) node [scale=2.5] (X) 
    {\begin{tabular}{l}
     $\{$  
     \!\includegraphics[scale=0.02]{../pics/o1.jpg},
     \includegraphics[scale=0.02]{../pics/o2.jpg},
     \!\includegraphics[scale=0.02]{../pics/o3.jpg},
     \includegraphics[scale=0.02]{../pics/o4.jpg},
     \!\includegraphics[scale=0.027]{../pics/o5.jpg}
     $\}$
    \end{tabular}};
    
    \draw (-5.6,-2.5) node [scale=2.5] (Y) 
    {\begin{tabular}{l}
     $\{$  
     \!\includegraphics[scale=0.059]{../pics/a1.jpg},
     \includegraphics[scale=0.048]{../pics/a2.jpg},
     \includegraphics[scale=0.02]{../pics/a3.jpg}
     $\}$
    \end{tabular}};
    
     \draw (0,1.5) node (X1) {5 elements};
     \draw (0,-3.5) node (y1) {3 elements};
  \end{tikzpicture}
  \end{center}

  \end{frame}
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  \begin{frame}[c]
  \frametitle{Newton vs Feynman}
  
  \begin{center}
  \begin{tabular}{cc}
  \includegraphics[scale=0.2]{../pics/newton.jpg} &
  \includegraphics[scale=0.2]{../pics/feynman.jpg}\\
  classical physics & quantum physics
  \end{tabular}
  \end{center}
  \end{frame}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

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  \begin{frame}[c]
  \frametitle{The Goal of the Talk}
 \large
  \begin{itemize}
  \item show you that something very unintuitive happens with very large sets	
  \bigskip\bigskip
  
  \item convince you that there are more {\bf problems} than {\bf programs}
  \end{itemize}	
  \end{frame}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\begin{frame}[t]
%
  \begin{center}
  \begin{tikzpicture}
 
  \draw (-5,2.5) node [scale=2.3] (X) 
    {\begin{tabular}{@ {\hspace{-3mm}}l}
     \bl{$B$ $=$ $\{$  
     \!\includegraphics[scale=0.02]{../pics/o1.jpg},
     \includegraphics[scale=0.02]{../pics/o2.jpg},
     \!\includegraphics[scale=0.02]{../pics/o3.jpg},
     \includegraphics[scale=0.02]{../pics/o4.jpg},
     \!\includegraphics[scale=0.027]{../pics/o5.jpg}
     $\}$}
    \end{tabular}};
    
    \draw (-6.6,-0.5) node [scale=2.3] (Y) 
    {\begin{tabular}{@ {\hspace{-3mm}}l}
     \bl{$A$ $=$ $\{$  
     \!\includegraphics[scale=0.059]{../pics/a1.jpg},
     \includegraphics[scale=0.048]{../pics/a2.jpg},
     \includegraphics[scale=0.02]{../pics/a3.jpg}
     $\}$}
     \end{tabular}};
  
     \only<1>{\draw (-5, -3) node[scale=2] 
       {\bl{$|A|$ $=$ $5$}, \bl{$|B|$ $=$ $3$}};}
     \only<2>{
       \draw [->, line width=1mm, red] (-7.4, 0.2) -- (-6.1, 2.1);
       \draw [->, line width=1mm, red] (-5.8, 0.2) -- (-3.1, 2.1);
       \draw [->, line width=1mm, red] (-4.5, 0.2) -- (-7.6, 2.1);
       \draw (-5, -3) node[scale=2] {then \bl{$|A|$ $\le$ $|B|$}};
       }
    \only<3>{
       \draw [<-, line width=1mm, red] (-7.5, 0.2) -- (-6.1, 2.1);
       \draw [<-, line width=1mm, red] (-7.3, 0.2) -- (-3.1, 2.1);
       \draw [<-, line width=1mm, red] (-6, 0.2) -- (-7.5, 2.1);
       \draw [<-, line width=1mm, red] (-4.5, 0.2) -- (-4.5, 2.1);
       \draw [<-, line width=1mm, red] (-4.3, 0.2) -- (-1.3, 2.1);
       
       \draw (-5, -3) node[scale=1.5] {\small{}for \bl{$=$}
        has to be a {\bf one-to-one} mapping};
       }

    
  \end{tikzpicture}
  \end{center}

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

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\begin{frame}[c]
\frametitle{Cardinality}

\Large
\bl{$|A|$} $\dn$ ``how many elements''\bigskip\\

\bl{$A \subseteq B  \Rightarrow |A| \leq |B|$}\bigskip\\\pause

if there is an injective function \bl{$f: A \rightarrow B$} then \bl{$|A| \leq |B|$}\

\begin{center}
\bl{\large$\forall x y.\; f(x) = f(y) \Rightarrow x = y$}
\end{center}
\end{frame}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%   

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

  \begin{center}
  \begin{tikzpicture}
  
  \draw (-6.6,2.5) node [scale=2.3] (X) 
    {\begin{tabular}{@ {\hspace{-3mm}}l}
     $A$ $=$ $\{$  
     \!\includegraphics[scale=0.02]{../pics/o1.jpg},
     \includegraphics[scale=0.02]{../pics/o2.jpg},
     \!\includegraphics[scale=0.02]{../pics/o3.jpg}
     $\}$
    \end{tabular}};
    
    \draw (-6.6,-0.5) node [scale=2.3] (Y) 
    {\begin{tabular}{@ {\hspace{-3mm}}l}
     $B$ $=$ $\{$  
     \!\includegraphics[scale=0.059]{../pics/a1.jpg},
     \includegraphics[scale=0.048]{../pics/a2.jpg},
     \includegraphics[scale=0.02]{../pics/a3.jpg}
     $\}$
     \end{tabular}};
   \onslide<3->{\draw (-7, -3) node[scale=1.5] 
      {then \bl{$|A|$ \alert{$=$} $|B|$}};}
     \only<1>{
       \draw [->, line width=1mm, red] (-7.4, 0.2) -- (-6.1, 2.1);
       \draw [->, line width=1mm, red] (-5.8, 0.2) -- (-4.3, 2.1);
       \draw [->, line width=1mm, red] (-4.5, 0.2) -- (-7.6, 2.1);
     }
    \only<2->{
       \draw [<-, line width=1mm, blue] (-7.5, 0.2) -- (-7.5, 2.1);
       \draw [<-, line width=1mm, blue] (-5.8, 0.2) -- (-4.3, 2.1);
       \draw [<-, line width=1mm, blue] (-4.5, 0.2) -- (-6.1, 2.1);
       }
   
    
  \end{tikzpicture}
  \end{center}

\end{frame}
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\begin{frame}[c]
\frametitle{Natural Numbers}

\Large
\bl{$\mathbb{N}$} \bl{$\dn$} \bl{$\{0, 1, 2, 3, .......\}$}\bigskip\pause 

\bl{$A$} is \alert{countable} iff \bl{$|A| \leq |\mathbb{N}|$}

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

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\begin{frame}[c]
\frametitle{First Question}

\Large
\bl{$|\mathbb{N} - \{0\}|   \;\;\;\alert{?}\;\;\;  |\mathbb{N}| $}\bigskip\bigskip 

\large
\bl{$\geq$} or \bl{$\leq$} or \bl{$=$} ?
\bigskip\bigskip\bigskip\pause

\bl{$x$ $\mapsto$ $x + 1$},\\  \bl{$|\mathbb{N} - \{0\}|$ $=$  
$|\mathbb{N}|$}
\end{frame}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%   

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\mode<presentation>{
\begin{frame}[c]

\Large
\bl{$|\mathbb{N} - \{0, 1\}|   \;\;\;\alert{?}\;\;\;  |\mathbb{N}| $}\bigskip\pause 

\bl{$|\mathbb{N} - \mathbb{O}|   \;\;\;\alert{?}\;\;\;  |\mathbb{N}| $}\bigskip\bigskip

\normalsize
\bl{$\mathbb{O}$} $\dn$ odd numbers\quad   \bl{$\{1,3,5......\}$}\\ \pause
\bl{$\mathbb{E}$} $\dn$ even numbers\quad   \bl{$\{0,2,4......\}$}\\
\end{frame}}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%   

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\mode<presentation>{
\begin{frame}[c]

\Large
\bl{$|\mathbb{N} \cup \mathbb{-N}|   \;\;\;\alert{?}\;\;\;  |\mathbb{N}| $}\bigskip\bigskip


\normalsize
\bl{$\mathbb{\phantom{-}N}$} $\dn$ positive numbers\quad   \bl{$\{0,1,2,3,......\}$}\\
\bl{$\mathbb{-N}$} $\dn$ negative numbers\quad   \bl{$\{0,-1,-2,-3,......\}$}\\
\end{frame}}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%  

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\mode<presentation>{
\begin{frame}[c]

\Large
\bl{$A$} is \alert{countable} if there exists an injective \bl{$f : A \rightarrow \mathbb{N}$}\bigskip

\bl{$A$} is \alert{uncountable} if there does not exist an injective \bl{$f : A \rightarrow \mathbb{N}$}\bigskip\bigskip 


countable:  \bl{$|A| \leq |\mathbb{N}|$}\\
uncountable:  \bl{$|A| > |\mathbb{N}|$}\pause\bigskip


Does there exist such an \bl{$A$} ?

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

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
  \mode<presentation>{
  \begin{frame}[c]
  \frametitle{Hilbert's Hotel}

  \begin{center}
 \includegraphics[scale=0.8]{../pics/hilberts_hotel.jpg}
  \end{center}

  \begin{itemize}
  \item \ldots has as many rooms as there are natural numbers
  \end{itemize}

  \end{frame}}
  %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%  
  
  
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\begin{frame}[t]
 \frametitle{\begin{tabular}{c}Real Numbers between\\[-2mm] 0 and 1\end{tabular}}

  \begin{center}
  \begin{tikzpicture}
  \draw [fill, color=black!50] (1,4) rectangle (2, 3);
  \draw [fill, color=black!50] (2,3) rectangle (3, 2);
  \draw [fill, color=black!50] (3,2) rectangle (4, 1);
  \draw [fill, color=black!50] (4,1) rectangle (5, 0);
  \draw (0, 0) grid (8, 5);
  \draw [line width = 1.mm] (1,0) -- (1, 5);    
  \draw [line width = 1.mm] (0, 4) -- (8, 4);    
  \draw (0.5,3.5) node {$1$};
  \draw (0.5,2.5) node {$2$};
  \draw (0.5,1.5) node {$3$};
  \draw (0.5,0.5) node {$4$};
  
  \draw (1.5,3.5) node {\only<1>{$3$}\only<2->{$4$}};
  \draw (2.5,3.5) node {$3$};
  \draw (3.5,3.5) node {$3$};
  \draw (4.5,3.5) node {$3$};
  \draw (5.5,3.5) node {$3$};
  \draw (6.5,3.5) node {$3$};
  \draw (7.5,3.5) node {$\ldots$};
  
  \draw (1.5,2.5) node {$1$};
  \draw (2.5,2.5) node {\only<1-2>{$2$}\only<3->{$3$}};
  \draw (3.5,2.5) node {$3$};
  \draw (4.5,2.5) node {$4$};
  \draw (5.5,2.5) node {$5$};
  \draw (6.5,2.5) node {$6$};
  \draw (7.5,2.5) node {$7$};

  \draw (1.5,1.5) node {$0$};
  \draw (2.5,1.5) node {$1$};
  \draw (3.5,1.5) node {\only<1-3>{$0$}\only<4->{$1$}};
  \draw (4.5,1.5) node {$1$};
  \draw (5.5,1.5) node {$0$};
  \draw (6.5,1.5) node {$\ldots$};
  
   \draw (1.5,0.5) node {$7$};
  \draw (2.5,0.5) node {$8$};
  \draw (3.5,0.5) node {$5$};
  \draw (4.5,0.5) node {\only<1-4>{$3$}\only<5->{$4$}};
  \draw (5.5,0.5) node {$9$};
  \draw (6.5,0.5) node {$\ldots$};
  
   \draw (1.5,-0.5) node {$\ldots$};
   \draw (8.5,3.5) node {$\ldots$};
  \end{tikzpicture}
  \end{center}
  \mbox{}\\[-20mm]\mbox{}
  
  \onslide<6->{
  \begin{center}
  \Large\bl{$|\mathbb{N}| < |R|$}
  \end{center}
  }

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


%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\mode<presentation>{
\begin{frame}[t]
 \frametitle{The Set of Problems}

  $\aleph_0$

  \begin{center}
  \begin{tikzpicture}
  \draw [fill, color=black!50] (1,4) rectangle (2, 3);
  \draw [fill, color=black!50] (2,3) rectangle (3, 2);
  \draw [fill, color=black!50] (3,2) rectangle (4, 1);
  \draw [fill, color=black!50] (4,1) rectangle (5, 0);
  \draw (0, 0) grid (8, 5);
  \draw [line width = 1.mm] (1,0) -- (1, 5);    
  \draw [line width = 1.mm] (0, 4) -- (8, 4);    
  \draw (0.5,3.5) node {$1$};
  \draw (0.5,2.5) node {$2$};
  \draw (0.5,1.5) node {$3$};
  \draw (0.5,0.5) node {$4$};
  
  \draw (1.5,4.5) node {$0$};
  \draw (2.5,4.5) node {$1$};
  \draw (3.5,4.5) node {$2$};
  \draw (4.5,4.5) node {$3$};
  \draw (5.5,4.5) node {$4$};
  \draw (6.5,4.5) node {$5$};
  \draw (7.5,4.5) node {$\ldots$}; 
  
  \draw (1.5,3.5) node {$0$};
  \draw (2.5,3.5) node {$1$};
  \draw (3.5,3.5) node {$0$};
  \draw (4.5,3.5) node {$1$};
  \draw (5.5,3.5) node {$0$};
  \draw (6.5,3.5) node {$1$};
  \draw (7.5,3.5) node {$\ldots$};
  
  \draw (1.5,2.5) node {$0$};
  \draw (2.5,2.5) node {$0$};
  \draw (3.5,2.5) node {$0$};
  \draw (4.5,2.5) node {$1$};
  \draw (5.5,2.5) node {$1$};
  \draw (6.5,2.5) node {$0$};
  \draw (7.5,2.5) node {$0$};

  \draw (1.5,1.5) node {$0$};
  \draw (2.5,1.5) node {$0$};
  \draw (3.5,1.5) node {$0$};
  \draw (4.5,1.5) node {$0$};
  \draw (5.5,1.5) node {$0$};
  \draw (6.5,1.5) node {$\ldots$};
  
   \draw (1.5,0.5) node {$1$};
  \draw (2.5,0.5) node {$1$};
  \draw (3.5,0.5) node {$0$};
  \draw (4.5,0.5) node {$1$};
  \draw (5.5,0.5) node {$1$};
  \draw (6.5,0.5) node {$\ldots$};
  
  \draw (1.5,-0.5) node {$\ldots$};
   \draw (8.5,3.5) node {$\ldots$};

  \end{tikzpicture}
  \end{center}
  
  
  \onslide<2>{
  \begin{center}
  \large \bl{|Progs| $=$ $|\mathbb{N}|$ $<$ |Probs|}
 \end{center}
  }


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


%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\mode<presentation>{
\begin{frame}[c]
\frametitle{Halting Problem}

\large
Assume a program \bl{$H$} that decides for all programs \bl{$A$} and all 
input data \bl{$D$} whether\bigskip

\begin{itemize}
\item \bl{$H(A, D) \dn 1$} iff \bl{$A(D)$} terminates
\item \bl{$H(A, D) \dn 0$} otherwise
\end{itemize}

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

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\mode<presentation>{
\begin{frame}[c]
\frametitle{Halting Problem (2)}

\large
Given such a program \bl{$H$} define the following program \bl{$C$}:
for all programs \bl{$A$}\bigskip

\begin{itemize}
\item \bl{$C(A) \dn 0$} iff \bl{$H(A, A) = 0$} 
\item \bl{$C(A) \dn$ loops} otherwise
\end{itemize}

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

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\mode<presentation>{
\begin{frame}[c]
\frametitle{Contradiction}


\bl{$H(C, C)$} is either \bl{$0$} or \bl{$1$}.

\begin{itemize}
\item \bl{$H(C, C) = 1$} $\stackrel{\text{def}\,H}{\Rightarrow}$ \bl{$C(C)\downarrow$} $\stackrel{\text{def}\,C}{\Rightarrow}$ \bl{$H(C, C)=0$} 
\item \bl{$H(C, C) = 0$} $\stackrel{\text{def}\,H}{\Rightarrow}$ \bl{$C(C)$} loops $\stackrel{\text{def}\,C}{\Rightarrow}$\\ 
\hspace{7cm}\bl{$H(C, C)=1$} 
\end{itemize}

Contradiction in both cases. So \bl{$H$} cannot exist.

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

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
  \mode<presentation>{
  \begin{frame}[c]
  \frametitle{Take Home Points}
 \large
 
  \begin{itemize}
  \item there are sets that are more infinite than others\bigskip
  \item even  with the most powerful computer we can imagine, there 
  are problems that cannot be solved by any program\bigskip\bigskip
  
  \item in CS we actually hit quite often such problems (halting problem)
  \end{itemize}

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

\end{document}

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