We can almost reach the Lie algebra of any isometry group in a single go. For every in the Lie algebra we must have:because has to be in the isometry group by definition as shown at Section "Lie algebra of a matrix Lie group".
Bibliography:
Eugene's background: www.quora.com/Who-is-Eugene-Khutoryansky/answer/Ciro-Santilli
How to develop Ciro Santilli's website before the OurBigBook migration by 
Ciro Santilli 37 Updated 2025-05-09 +Created 1970-01-01
Ciro Santilli 37 Updated 2025-05-09 +Created 1970-01-01The website moved from AsciiDoctor to OurBigBook Markup in 2020, making this section mostly useless. But hey, history!
The source code is located at: github.com/cirosantilli/cirosantilli.github.io
Build locally, watch for changes and rebuild automatically, and start a local server with:
git clone --recursive https://github.com/cirosantilli/cirosantilli.github.io
cd cirosantilli.github.io
bundle install
npm install
./runSource:
./run.The website will be visible at: localhost:4000.
Tested on the latest Ubuntu.
Publish changes to GitHub Pages:
git add -u
git commit -m 'make yourself look sillier'
./publishSource:
./publish.GitHub forces us to use the master branch for the build output... so the actual source is in the branch
dev.Update the gems with:
bundle update
git add Gemfile.lock
git commit -m 'update gems'His website was originally written in markdown, however those were deprecated in favour of AsciiDoctor when Ciro saw the light, rationale shown at: markdown-style-guideuse-asciidoc
GitHub pages is chosen instead of a single page GitHub README.adoc for the following reasons:
- Ciro will want some unsupported extensions, notably mathematics, likely with KaTeX server side:
- github.com/asciidoctor/asciidoctor/pull/3338
- stackoverflow.com/questions/11256433/how-to-show-math-equations-in-general-githubs-markdownnot-githubs-blog
- g14n.info/2014/09/math-on-github-pages/
- stackoverflow.com/questions/11256433/how-to-show-math-equations-in-general-githubs-markdownnot-githubs-blog
- www.quora.com/How-can-I-combine-latex-and-markdown-in-GitHub
- when GitHub dies, Ciro's website URL still lives and retains the PageRank!
2019 cell phones are glued together with adhesive, which makes them impossible to repair them unless you have a heat gun, spend hours and hours learning and planning, and accept the risk of breaking the screen
Repairability scores: www.ifixit.com/smartphone-repairability
If you take a phone less than 300 dollars to a repair shop in the first world, they will say: I've never repaired this crap, and likely for the price of the repair you should just buy a new one, and so to the trash goes the old one, polluting the planet, and in comes a new one, enriching the manufacturer further.
Oh, there is some 2017 EU action actually: (archive) www.europarl.europa.eu/news/en/press-room/20170629IPR78633/making-consumer-products-more-durable-and-easier-to-repair
Pinned article: ourbigbook/introduction-to-the-ourbigbook-project
Welcome to the OurBigBook Project! Our goal is to create the perfect publishing platform for STEM subjects, and get university-level students to write the best free STEM tutorials ever.
Everyone is welcome to create an account and play with the site: ourbigbook.com/go/register. We belive that students themselves can write amazing tutorials, but teachers are welcome too. You can write about anything you want, it doesn't have to be STEM or even educational. Silly test content is very welcome and you won't be penalized in any way. Just keep it legal!
Intro to OurBigBook
. Source. We have two killer features:
- topics: topics group articles by different users with the same title, e.g. here is the topic for the "Fundamental Theorem of Calculus" ourbigbook.com/go/topic/fundamental-theorem-of-calculusArticles of different users are sorted by upvote within each article page. This feature is a bit like:
- a Wikipedia where each user can have their own version of each article
- a Q&A website like Stack Overflow, where multiple people can give their views on a given topic, and the best ones are sorted by upvote. Except you don't need to wait for someone to ask first, and any topic goes, no matter how narrow or broad
This feature makes it possible for readers to find better explanations of any topic created by other writers. And it allows writers to create an explanation in a place that readers might actually find it.
Figure 1. Screenshot of the "Derivative" topic page. View it live at: ourbigbook.com/go/topic/derivativeVideo 2. OurBigBook Web topics demo. Source. - local editing: you can store all your personal knowledge base content locally in a plaintext markup format that can be edited locally and published either:This way you can be sure that even if OurBigBook.com were to go down one day (which we have no plans to do as it is quite cheap to host!), your content will still be perfectly readable as a static site.
- to OurBigBook.com to get awesome multi-user features like topics and likes
- as HTML files to a static website, which you can host yourself for free on many external providers like GitHub Pages, and remain in full control
Figure 2. You can publish local OurBigBook lightweight markup files to either OurBigBook.com or as a static website.
Figure 3. Visual Studio Code extension installation.
Figure 5. . You can also edit articles on the Web editor without installing anything locally. Video 3. Edit locally and publish demo. Source. This shows editing OurBigBook Markup and publishing it using the Visual Studio Code extension. 
- Infinitely deep tables of contents:
All our software is open source and hosted at: github.com/ourbigbook/ourbigbook
Further documentation can be found at: docs.ourbigbook.com
Feel free to reach our to us for any help or suggestions: docs.ourbigbook.com/#contact