When I came, two Bell GU4 (MR11) 20W 12v.
One burnt. Put in an ASDA halogen one.
ASDA burnt, put in TopLux on right, old Bell left.
2019-01-24, right one burnt a few days ago, old Bell still works. Inner part black, and black dot on the wire. Putting new TopLux again, but this time on the left, old bell on right.
2019-01-24 toilet top lamp also burnt a few days ago, but not at the same time as mirror. Diall, 240V 40W, GU10. Putting in IKEA 240V 35W.
2019-02-02 toilet mirror lamp left (TopLux) burnt. Don't know what to do anymore. Only the magic Bell lamp works.
2019-03-06 toilet top lamp left burnt, IKEA 240V 35W GU10. Putting in another one.
2019-03-28 toilet top lamp right burnt, IKEA 240V 35W GU10. Waiting for people to come to look at transformer, there is definitely something wrong.
2019-04-03 top lamps: replaced with LED (LAP GU10 3W) since lower power, transformer not changed. Mirror lamps: transformer changed, left one replaced with Homebase Halogen 20W 12V. When I came back lamps flickering badly and sometimes not turning on, recalled technician.
2019-04-12 mirror lamp: it was just he connector that was bad, it was changed, also put LEDs there to make it less warm and hopefully have less tear on connector.
Source code:
- github.com/leanprover/lean4 why a separate repo per version... but it is what it is.
- github.com/leanprover/lean
They are huge fans of Unicode characters! Check this out from a formal proof of the prime number theorem: github.com/AlexKontorovich/PrimeNumberTheoremAnd/blob/fbdbb5310d036d33b9797b35f3b04b08f2447a6e/PrimeNumberTheoremAnd/ZetaBounds.lean
Their dependency graph thingy is just beautiful however: alexkontorovich.github.io/PrimeNumberTheoremAnd/web/dep_graph_document.html
Biologists are obsessed with these!
- phaser/hello.html: a minimal hello world adapted from web.archive.org/web/20230323212804/https://phaser.io/tutorials/getting-started-phaser3/part5. Not an actual game strictly speaking though, just shows the phaser logo bouncing around the screen.
- phaser/hello-game.html: an actually hello world game where you have to collect stars and avoid bombs.Based on labs.phaser.io/index.html?dir=games/firstgame/&q=:
- finished version: labs.phaser.io/view.html?src=src/games/firstgame/part10.js
- corresponding tutorial: web.archive.org/web/20230323210501/https://phaser.io/tutorials/making-your-first-phaser-3-game/part10.
We ust use the if mod notation definition as mentioned at: math.stackexchange.com/questions/4305972/what-exactly-is-a-collatz-like-problem/4773230#4773230
The Busy Beaver Competition: a historical survey by Pascal Michel by 
Ciro Santilli 37 Updated 2025-07-16
Ciro Santilli 37 Updated 2025-07-16 Pinned article: 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