Twin prime conjecture by Ciro Santilli 40 Updated 2025-07-16
Let's show them how it's done with primes + awk. Edit. They have a -d option which also shows gaps!!! Too strong:
sudo apt install bsdgames
primes -d 1 100 | awk '/\(2\)/{print $1 - 2, $1 }'
gives us the list of all twin primes up to 100:
0 2
3 5
5 7
11 13
17 19
29 31
41 43
59 61
71 73
Tested on Ubuntu 22.10.
Tree representation by Ciro Santilli 40 Updated 2025-07-16
This section is about ways in which you can represent a tree.
Trees are a specific type of graph, so any graph representation also provides a way to represent a tree.
Therefore this section will focus only on methods specific to tress, and which cannot be used for graphs in general.
bsdgames by Ciro Santilli 40 Updated 2025-07-16
There is great beauty here. Great beauty. It's pure terminal poetry.
The most canonical source code Ciro Santilli can find right now is: sources.debian.org/src/bsdgames/
There is just one key gotcha: the project has to be useful.
Physics engine by Ciro Santilli 40 Updated 2025-07-16
There is no clear distinction between "serious simulations" and "physics engines", it's just that "physics engine" have a "for video game" connotation.
And especially, in the context of gaming, it usually means "rigid body dynamics simulation" in particular.
Jimi Hendrix by Ciro Santilli 40 Updated 2025-07-16
  • Are you experienced. OMG that album...
As a phisicist once amazingly put it in a talk Ciro watched:
It all depends on how much energy you have to probe nature with. Previously, we thought protons were elementary particles. But then we used more energy and found that they aren't.
If some alien race had even less energy, they might not know about electrons at all, and could think that anyons are actually elementary.
Being an "elementary particle" is always a possibly temporary label.
Game of chance by Ciro Santilli 40 Updated 2025-07-16
The definition is not very precise, as in many games with random elements there is a mixture of both skill and luck.
So we just use the precise Non-deterministic game term instead for any game that has any random element beyond the control of the players.
A good definition is that the sparse matrix has non-zero entries proportional the number of rows. Therefore this is Big O notation less than something that has non zero entries. Of course, this only makes sense when generalizing to larger and larger matrices, otherwise we could take the constant of proportionality very high for one specific matrix.
Of course, this only makes sense when generalizing to larger and larger matrices, otherwise we could take the constant of proportionality very high for one specific matrix.

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!
We have two killer features:
  1. 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-calculus
    Articles 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/derivative
  2. 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.
    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.
  3. https://raw.githubusercontent.com/ourbigbook/ourbigbook-media/master/feature/x/hilbert-space-arrow.png
  4. Infinitely deep tables of contents:
    Figure 6.
    Dynamic article tree with infinitely deep table of contents
    .
    Descendant pages can also show up as toplevel e.g.: ourbigbook.com/cirosantilli/chordate-subclade
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