undirected Graph with 6 nodes. In Red is the maximal 2-clique of the Graph
<a href="//commons.wikimedia.org/wiki/User:Tavin" title="User:Tavin">Tavin</a>
<a href="//commons.wikimedia.org/wiki/File:6n-graf-clique.svg" title="File:6n-graf-clique.svg">File:6n-graf-clique.svg</a>