Subgraph of the graph of world countries where edges connect the countries which share a border, displaying eight Eurasian countries and some of their borders. This graph is a suvdivision of the complete graph K5, which proves that the graph of world countries is not planar due to Kuratowski's theorem. This is possible because Azerbaijan's territory is not connected: only the exclave of Nakhchivan borders Turkey.
<a href="//commons.wikimedia.org/wiki/User:GrandEscogriffe" title="User:GrandEscogriffe">GrandEscogriffe</a>
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<span class="int-own-work" lang="en">Own work</span>