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<p>of the same size in the blue graph.</p>

<p><big>Coloring triangle-free graphs</big></p>
<p>Much research about triangle-free graphs has focused on <a href="page.php?w=graph_coloring">graph coloring</a>. Every <a href="page.php?w=bipartite_graph">bipartite graph</a> (that is, every 2-colorable graph) is triangle-free, and <a href="page.php?w=Gr%C3%B6tzsch%27s_theorem">Grötzsch's theorem</a> states that every triangle-free <a href="page.php?w=planar_graph">planar graph</a> may be 3-colored. However, nonplanar triangle-free graphs may require many more</p><p>
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