\documentclass[tikz,convert={outfile=\jobname.svg}]{standalone}

% This is a LaTeX file that uses a package called "tikz".  To include a tikz
% image in your document, put \usepackage{tikz} and any \usetikzpackage{...}
% commands between \documentclass{...} and \begin{document}.  Everything between
% \begin{tikzpicture} and \end{tikzpicture} defines the picture.

\usetikzlibrary{shapes.symbols}

\begin{document}


\begin{tikzpicture}
\node (nfa)  at (-3,0) {NFA};
\node (dfa)  at (3,0) {DFA};
\node (re)   at (0,-3) {regular expression};
\node (gnfa) at (-1.5, -1.5) {generalized NFA};
\node (enfa) at (1.5,-1.5) {$\varepsilon$-NFA};

\draw[->,>=stealth]
  (nfa)  edge[bend left] node[above] {power set} (dfa)
  (dfa)  edge            node[above] {trivial} (nfa)
  (nfa)  edge[bend right] node[left] {trivial} (gnfa)
  (gnfa) edge[bend right] node[left] {remove nodes} (re)
  (re)   edge[bend right] node[right] {struct. ind.} (enfa)
  (enfa) edge[bend right] node[right] {powerset} (dfa)
;

\end{tikzpicture}

\end{document}
