I really enjoyed this article.  It&#x27;s great to learn more about groups having been aware of nice properties like closure and identity when designing new data types and the procedures that operate on them.  While it doesn&#x27;t discuss group theory explicitly, SICP&#x27;s section 2.2 does a great job showing the power of closure.<p><a href="https:&#x2F;&#x2F;sarabander.github.io&#x2F;sicp&#x2F;html&#x2F;2_002e2.xhtml#g_t2_002e2" rel="nofollow">https:&#x2F;&#x2F;sarabander.github.io&#x2F;sicp&#x2F;html&#x2F;2_002e2.xhtml#g_t2_00...</a>