The <a href="https://en.wikipedia.org/wiki/complete_graph" class="extiw" title="en:complete graph">complete graph</a> of order 4, K<sub>4</sub>.
<a href="//commons.wikimedia.org/wiki/User:Joey-das-WBF" title="User:Joey-das-WBF">Johannes Rössel</a> (<a href="//commons.wikimedia.org/wiki/User_talk:Joey-das-WBF" title="User talk:Joey-das-WBF"><span class="signature-talk">talk</span></a>)
<span class="int-own-work" lang="en">Own work</span>