I have poor English, and PPAP. @unknown@mathstodon.xyz

mathstodon.xyz is now running Mastodon v2.9.2!
The big new feature this time is the single-column layout, which looks more like standard Twitter. It's the default layout for new users. Existing users can switch to it on the preferences page.
Full release notes: https://github.com/tootsuite/mastodon/releases/tag/v2.9.0

Les Éléments de l'Art Arabe, https://archive.org/details/LesElementsDeLArtArabeBourgoin/page/n1

Lots of plates of pretty geometric girih patterns, from an 1879 book by Jules Bourgoin. Via a comment at https://www.metafilter.com/181967/geometry-and-ornament-in-Islamic-architecture

新しい絵文字が到着しました！

Mathematical Objects: Stick of Chalk

A conversation about mathematics inspired by a stick of chalk. Presented by Katie Steckles and Peter Rowlett. Podcast: Play in new window | Download Subscribe: Android | Google Podcasts | RSS https://aperiodical.com/2019/04/mathematical-objects-stick-of-chalk/

Regular polygon surfaces: https://arxiv.org/abs/1804.05452
Ian Alevy answers Problem 72 of The Open Problems Project (http://cs.smith.edu/~jorourke/TOPP/P72.html#Problem.72): every topological sphere made of regular pentagons can be constructed by gluing regular dodecahedra together.

You can also glue dodecahedra to get higher-genus surfaces, as in this image from https://momath.org/mathmonday/the-paragons-system/, but Alevy's theorem doesn't apply, so we don't know whether all higher-genus regular-pentagon surfaces are formed that way.

Another one of my domain coloring stuff from my archives: an iterated rational function with icosahedral symmetry, plotted over the Riemann sphere

Mathematical sign language: https://aperiodical.com/2019/04/mathematical-sign-language-interview-with-dr-jess-boland/

Hearing-impaired eletrical engineering researcher Jess Boland discovered that weren't enough technical terms in British Sign Language to cover the mathematics she uses in her work, so she's been creating new ones as well as promoting the ones BSL already had. Katie Steckles interviews her for The Aperiodical.

(@aperiodical has a Mathstodon account but they're letting it go stale instead of promoting their new posts...)

We've blogged about #Halcyon 2.3.0,what we did especially in this release and also a few things before.You can read it here: https://nikisoft.myblog.de/nikisoft/art/11669027/Halcyon-2-3-0-Polls-are-coming-to-Mastodon
Additionally new strings of Halcyon 2.3.0 are now ready for translation at https://translate.zanata.org/iteration/view/halcyon/2.3.0 .We need your help for offering Halcyon in even more languages and to update existing languages.Thank you very much for your help!

投稿が届いたときの署名を検証するのですが、マストドンなどではPKCS＃8が使われており、misskeyではPKCS＃1が使われています。そこで変換する必要があるのですが、内部でずぼらしていて、いわゆる"MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8A"をくっつける手法を使っていたのですが、鍵長が変わって使えなくなったのでした。結局処理コストが少し掛かりますがopensslを呼び出して変換するようにしました。
https://mstdn.nere9.help/@osapon/101926969819723695

I've just updated mathstodon.xyz to Mastodon v2.8.0.
Release notes: https://github.com/tootsuite/mastodon/releases/tag/v2.8.0
It's got polls, an interface to manage your follow lists, and lets us change signups from open access to "ask for an invitation". We'll do that if spam becomes a problem again (it currently isn't)

Google+一般の部終了という師匠亡き後の、初のアップデートです。
・タイムラインのトゥート間の隙間を調整（各ブラウザの差異を埋めるべく）
・ブースト機能の拡張（設定画面で切り替えが必要です）
・Pleromaにようやく対応
などなど、詰め込みすぎた感がありますが詳細は下記をご覧ください。
https://github.com/nishlumi/gplusdon/releases/tag/1.0.15-20190407

相当長い時間かけて修正しては確認を繰り返したので大丈夫なはずですが、今回内部的にも外見的にも色々変わっています。
何かありましたら早急に対応いたしますので引き続きよろしくお願いします。

#quesdon 本家の未回答質問をQuesdon(toot.app)にインポートできるようになりました。
平成の残りもゆったりとお過ごしください。
https://quesdon.toot.app

What we'll see when Andromeda and the Milky Way collide! https://twitter.com/universal_sci/status/1112830219071651841/photo/1
#newsbot

We're proud to announce that #Halcyon has been bought by @facebook .We're looking forward to a cooperation which will bring advantages for both platforms.Let's make federated social media for the masses together!We thank everyone who went the long way with us.Nothing will change for you as a user except that we will abuse every action you do for advertising.Oh by the way ads will be introduced with the next release!Find out more here: https://nikisoft.one/firstapril.php

Interesting…
\[\begin{align}\sqrt[3]{50+\sqrt{2527}}&+\sqrt[3]{50-\sqrt{2527}}=4\\
\sqrt[3]{85+\sqrt{7252}}&+\sqrt[3]{85-\sqrt{7252}}=5\\
\sqrt[3]{44+\sqrt{1944}}&+\sqrt[3]{44-\sqrt{1944}}=4\\
\sqrt[3]{1414+\sqrt{1999404}}&+\sqrt[3]{1414-\sqrt{1999404}}=14\\
\sqrt[3]{3515+\sqrt{12355252}}&+\sqrt[3]{3515-\sqrt{12355252}}=19\\
\sqrt[3]{171710+\sqrt{29484324108}}&+\sqrt[3]{171710-\sqrt{29484324108}}=70\\
\sqrt[3]{3015103+\sqrt{9090846100636}}&+\sqrt[3]{3015103-\sqrt{9090846100636}}=182\end{align}\]

I'm looking for identities like this one that I've already found:
\[\sqrt[3]{4n^3+6n+\sqrt{16n^6+48n^4+36n^2+8}}+\sqrt[3]{4n^3+6n-\sqrt{16n^6+48n^4+36n^2+8}}=2n\]

I can't think of a better way of distributing the code we use to add #LaTeX to mathstodon.xyz, so I've made a GitHub gist containing a patch file: https://gist.github.com/christianp/617d5673fb28d130d552253182315af4
It also includes a patch to add the automatic replacement of some LaTeX #math commands with #unicode equivalents inside the toot compose box, which is more convenient when you don't need "proper" LaTeX typesetting.

こういうの思いつきました(*´ω｀*)