<p>"Borromean chain-mail" -- an indefinitely extended pattern in which each small circle is part of four <a href="//commons.wikimedia.org/wiki/File:Borromeanrings.png" title="File:Borromeanrings.png">Borromean rings</a> configurations, and each large circle is part of eight Borromean rings configurations (so that every area contained within circles of three different colors is at the center of a Borromean rings configuration, and no two circles are directly linked).
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To free a yellow or blue loop, two red loops or two green loops must be cut.  To free a red or green loop, four other loops must be cut.
<ul><li><a href="//commons.wikimedia.org/wiki/File:Borromean-chainmail-tile.png" title="File:Borromean-chainmail-tile.png">Borromean-chainmail-tile.png</a>: <a href="//commons.wikimedia.org/wiki/User:AnonMoos" title="User:AnonMoos">AnonMoos</a></li>
<li>derivative work: <a href="//commons.wikimedia.org/wiki/User:McSush" title="User:McSush">McSush</a> (<a href="//commons.wikimedia.org/wiki/User_talk:McSush" title="User talk:McSush"><span class="signature-talk">talk</span></a>)</li></ul>
<ul><li><a href="//commons.wikimedia.org/wiki/File:Borromean-chainmail-tile.png" title="File:Borromean-chainmail-tile.png">Borromean-chainmail-tile.png</a></li></ul>