In this section we document the outcomes of more detailed inspection of both the communication mechanisms (JavaScript, JAR, swf) and HTML that might help to better fingerprint the websites.
Order (algebra) by Ciro Santilli 37 Updated 2025-07-16
The order of a algebraic structure is just its cardinality.
Sometimes, especially in the case of structures with an infinite number of elements, it is often more convenient to talk in terms of some parameter that characterizes the structure, and that parameter is usually called the degree.
Normal subgroup by Ciro Santilli 37 Updated 2025-07-16
Only normal subgroups can be used to form quotient groups: their key definition is that they plus their cosets form a group.
One key intuition is that "a normal subgroup is the kernel" of a group homomorphism, and the normal subgroup plus cosets are isomorphic to the image of the isomorphism, which is what the fundamental theorem on homomorphisms says.
Therefore "there aren't that many group homomorphism", and a normal subgroup it is a concrete and natural way to uniquely represent that homomorphism.
The best way to think about the, is to always think first: what is the homomorphism? And then work out everything else from there.
Ring signature by Ciro Santilli 37 Updated 2025-07-16
Used for example:
Working remotely is hard if you don't already highly master the software and enterprise systems used.
Also you don't feel people's love as strongly, and usefulness is built on love, see also Steve Jobs's Pixar office space design philosophy.
But please, give workers a small silent office so that we can concentrate instead of a silly open space, and create an internal social network so people can see what others are doing.
Remote working is much better if the majority of the team also does it, otherwise you will get excluded. Maybe after VR...
Standard cell library by Ciro Santilli 37 Updated 2025-07-16
Basically what register transfer level compiles to in order to achieve a real chip implementation.
After this is done, the final step is place and route.
The standard cell library is typically composed of a bunch of versions of somewhat simple gates, e.g.:
  • AND with 2 inputs
  • AND with 3 inputs
  • AND with 4 inputs
  • OR with 2 inputs
  • OR with 3 inputs
and so on.
Each of those gates has to be designed by hand as a 3D structure that can be produced in a given fab.
Simulations are then carried out, and the electric properties of those structures are characterized in a standard way as a bunch of tables of numbers that specify things like:
  • how long it takes for electrons to pass through
  • how much heat it produces
Those are then used in power, performance and area estimates.
HyperPhysics by Ciro Santilli 37 Updated 2025-07-16
Created by Dr. Rod Nave from Georgia State University, where he worked from 1968 after his post-doc in North Wales on molecular spectroscopy.
While there is value to that website, it always feels like it falls a bit too short as too "encyclopedic" and too little "tutorial-like". Most notably, it has very little on the history of physics/experiments.
Ciro Santilli likes this Rod, he really practices some good braindumping, just look at how he documented his life in the pre-social media Internet dark ages: hyperphysics.phy-astr.gsu.edu/Nave-html/nave.html
The website evolved from a HyperCard stack, as suggested by the website name, mentioned at: hyperphysics.phy-astr.gsu.edu/hbase/index.html.
exhibits.library.gsu.edu/kell/exhibits/show/nave-kell-hall/capturing-a-career has some good photo selection focused on showing the department, and has an interview.
Lie group by Ciro Santilli 37 Updated 2025-07-16
The key and central motivation for studying Lie groups and their Lie algebras appears to be to characterize symmetry in Lagrangian mechanics through Noether's theorem, just start from there.
Notably local symmetries appear to map to forces, and local means "around the identity", notably: local symmetries of the Lagrangian imply conserved currents.
The fact that there are elements arbitrarily close to the identity, which is only possible due to the group being continuous, is the key factor that simplifies the treatment of Lie groups, and follows the philosophy of continuous problems are simpler than discrete ones.
Bibliography:
Video 1.
What is Lie theory? by Mathemaniac 2023
. Source.
E91 by Ciro Santilli 37 Updated 2025-07-16
Requires entangled particles, unlike BB84 which does not.
PageRank by Ciro Santilli 37 Updated 2025-07-16
When Ciro finally understood that this is a play on Larry Page's name (of course it is, typical programmer/academic humor stuff), his mind blew.

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