Andrew D. Hwang<p>I'm delighted to announce the new version of Differential Geometry, my math blog and online shop, and warmly invite you to visit <a href="https://www.diffgeom.com" rel="nofollow noopener noreferrer" translate="no" target="_blank"><span class="invisible">https://www.</span><span class="">diffgeom.com</span><span class="invisible"></span></a> to see all that's new!</p><p>As a special thank-you for your interest and support, please use the discount code DG-Math through Sunday, June 1, for 15% off clothing and wall decor.</p><p><a href="https://mathstodon.xyz/tags/Math" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>Math</span></a> <a href="https://mathstodon.xyz/tags/MathArt" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>MathArt</span></a></p>