Sample of graph edge coloring: Dürer graph. Layout from <a href="//commons.wikimedia.org/wiki/User:Namitsu" title="User:Namitsu">Namitsu</a> (<a href="//commons.wikimedia.org/w/index.php?title=File:Graphe_durer.png&amp;action=edit&amp;redlink=1" class="new" title="File:Graphe durer.png (page does not exist)">File:Graphe durer.png</a>).
<a href="//commons.wikimedia.org/wiki/User:Koko90" title="User:Koko90">Koko90</a>
CC BY-SA 3.0
<span class="int-own-work" lang="en">Own work</span>