%%
%% Ein Beispiel der DANTE-Edition
%%
%% 2. Auflage
%%
%% Beispiel 15-04-23 auf Seite 777.
%%
%% Copyright (C) 2016 Herbert Voss
%%
%% It may be distributed and/or modified under the conditions
%% of the LaTeX Project Public License, either version 1.3
%% of this license or (at your option) any later version.
%%
%% See
http://www.latex-project.org/lppl.txt for details.
%%
%%
%% ====
% Show page(s) 1
%%
%%
\documentclass[]{exaarticle}
\pagestyle{empty}
\setlength\textwidth{193.16928pt}
\usepackage[T1]{fontenc}
%StartShownPreambleCommands
\usepackage{tikz}
\usetikzlibrary{fit}
\pgfdeclarelayer{foreground} \pgfdeclarelayer{background}
\pgfsetlayers{background,main,foreground}
%StopShownPreambleCommands
\begin{document}
\begin{tikzpicture}
[Kreis/.style={circle,draw=blue!50,fill=blue!20,thick},
Rechteck/.style={rectangle,draw=black!50,fill=black!20,thick},bend angle=45,
pre/.style={<-,shorten <=1pt,semithick}, post/.style={->,shorten >=1pt,semithick}]
\node[Kreis] (K1) {}; \node[Kreis] (K2) [below of=K1] {};
\node[Kreis] (K3) [below of=K2] {}; \node[Rechteck] (R_1) [right of=K2] {}
edge [pre] node[auto] {1} (K2) edge [post,bend right] node[auto,swap] {2}(K1)
edge [pre,bend left] node[auto] {3} (K3);
\node[Rechteck] (R_2) [left of=K2] {}
edge [post] node[auto] {A} (K2)
edge [pre,bend left] node[auto] {B} (K1)
edge [post,bend right] node[auto,swap] {C} (K3);
\begin{pgfonlayer}{background}
\node [fill=black!20,fit=(K1)(K3)(R_1)(R_2)] {};
\end{pgfonlayer}
\end{tikzpicture}
\end{document}
