The JavaScript of each website appears to be quite small and similarly sized. They are all minimized, but have reordered things around a bit.
First we have to know that the Wayback Machine adds some stuff before and after the original code. The actual code there starts at:
ap={fg:['MSXML2.XMLHTTP
and ends in:
ck++;};return fu;};
We can use a JavaScript beautifier such as beautifier.io/ to be abe to better read the code.
It is worth noting that there's a lot of <script> tags inline as well, which seem to matter.
Further analysis would be needed.
Here we list public domain academic papers. They must be public domain in the country of origin, not just the US, which had generally less stringent timings with the 95 year after publication rule rather than life + 70, which often ends up being publication + 110/120. Once these are reached, they may be upload to Wikimedia Commons!
Set (mathematics) by Ciro Santilli 40 Updated 2025-07-16
Intuitively: unordered container where all the values are unique, just like C++ std::set.
More precisely for set theory formalization of mathematics:
  • everything is a set, including the elements of sets
  • string manipulation wise:
    • {} is an empty set. The natural number 0 is defined as {} as well.
    • {{}} is a set that contains an empty set
    • {{}, {{}}} is a set that contains two sets: {} and {{}}
    • {{}, {}} is not well formed, because it contains {} twice
Created by MongoDB, attempts to be even more restrictive than AGPL by more explicitly saying that indirect automatic requests are also included in the "you must give source" domain: opensource.stackexchange.com/questions/8025/difference-between-mongodb-sspl-and-gnu-agpl
The base use case is:
which is what MongoDB is trying to ensure, which sounds fair.
Set function by Ciro Santilli 40 Updated 2025-07-16
This section is about functions that operates on arbitrary sets.

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 2.
    You can publish local OurBigBook lightweight markup files to either https://OurBigBook.com or as a static website
    .
    Figure 3.
    Visual Studio Code extension installation
    .
    Figure 4.
    Visual Studio Code extension tree navigation
    .
    Figure 5.
    Web editor
    . 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.
    Video 4.
    OurBigBook Visual Studio Code extension editing and navigation demo
    . Source.
  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