# Example: The seven bridges of Königsberg

Published 2009-08-23 | Author: Alain Matthes

The Seven Bridges of Königsberg is a famous historical problem in mathematics. Its negative resolution by Leonhard Euler in 1735 laid the foundations of graph theory and presaged the idea of topology.

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% The seven bridges of Königsberg
% Author : Alain Matthes
% Encoding : UTF8
% Engine : PDFLaTeX
\documentclass[]{article}
\usepackage[utf8]{inputenc}
\usepackage{fullpage}
\usepackage{fourier}
\usepackage{tikz}
\usetikzlibrary{arrows,%
shapes,positioning}

\thispagestyle{empty}
\begin{document}

The Seven Bridges of Königsberg is a famous historical problem in mathematics. Its negative resolution by Leonhard Euler in 1735 laid the foundations of graph theory and presaged the idea of topology.

Abstract graph corresponding to bridges of Königsberg

\begin{center}
\begin{tikzpicture}[node distance   = 4 cm]
\useasboundingbox (-1,-1) rectangle (11,11);
\tikzset{VertexStyle/.style = {shape          = circle,
ball color     = orange,
text           = black,
inner sep      = 2pt,
outer sep      = 0pt,
minimum size   = 24 pt}}
\tikzset{EdgeStyle/.style   = {thick,
double          = orange,
double distance = 1pt}}
\tikzset{LabelStyle/.style =   {draw,
fill           = yellow,
text           = red}}
\node[VertexStyle](A){A};
\node[VertexStyle,right=of A](B){B};
\node[VertexStyle,right=of B](C){C};
\node[VertexStyle,above= 8 cm of B](D){D};
\draw[EdgeStyle](B) to node[LabelStyle]{1} (D) ;
\tikzset{EdgeStyle/.append style = {bend left}}
\draw[EdgeStyle](A) to node[LabelStyle]{2} (B);
\draw[EdgeStyle](B) to node[LabelStyle]{3} (A);
\draw[EdgeStyle](B) to node[LabelStyle]{4} (C);
\draw[EdgeStyle](C) to node[LabelStyle]{5} (B);
\draw[EdgeStyle](A) to node[LabelStyle]{6} (D);
\draw[EdgeStyle](D) to node[LabelStyle]{7} (C);

\end{tikzpicture}
\end{center}
\end{document}


• #1 Alain Matthes, August 23, 2009 at 2:34 p.m.

HI,

i forget to use LabelStyle

 \draw[EdgeStyle](B) to node[LabelStyle]{1} (D) ;
\tikzset{EdgeStyle/.append style = {bend left}}
\draw[EdgeStyle](A) to node[LabelStyle]{2} (B);
\draw[EdgeStyle](B) to node[LabelStyle]{3} (A);
\draw[EdgeStyle](B) to node[LabelStyle]{4} (C);
\draw[EdgeStyle](C) to node[LabelStyle]{5} (B);
\draw[EdgeStyle](A) to node[LabelStyle]{6} (D);
\draw[EdgeStyle](D) to node[LabelStyle]{7} (C);


Sorry :(

Alain

• #2 Kjell Magne Fauske, August 23, 2009 at 7:53 p.m.

I have updated the example with the new code.

• #3 Jérome, June 21, 2012 at 5:06 p.m.

Hi, you should replace

\nodeVertexStyle,right=of A{B}; \nodeVertexStyle,right=of B{C}; \nodeVertexStyle,above= 8 cm of B{D};

by

\nodeVertexStyle,right of = A{B}; \nodeVertexStyle,right of = B{C}; \nodeVertexStyle,above of = B{D};

The "=" signe is miss placed - according to the manual v2.0 and my compilers: pdfTeX 3.1415926-1.40.10-2.2 (TeX Live 2009/Debian)

Cheers.