1 \documentclass{article}

     2 

     3 \usepackage{tikz}

     4 \usetikzlibrary{automata,positioning}

     5 \begin{document}

     6 \section{regular expression derivatives as NFA's}

     7 \begin{tikzpicture}[shorten >=1pt,node distance=2cm,on grid,auto] 

     8    \node[state,initial] (q_0)   {$q_0$}; 

     9    \node[state] (q_1) [above right=of q_0] {$q_1$}; 

    10    \node[state] (q_2) [below right=of q_0] {$q_2$}; 

    11    \node[state,accepting](q_3) [below right=of q_1] {$q_3$};

    12     \path[->] 

    13     (q_0) edge  node {0} (q_1)

    14           edge  node [swap] {1} (q_2)

    15     (q_1) edge  node  {1} (q_3)

    16           edge [loop above] node {0} ()

    17     (q_2) edge  node [swap] {0} (q_3) 

    18           edge [loop below] node {1} ();

    19 \end{tikzpicture}

    20 \end{document}