Covariant derivative by Ciro Santilli 37 Updated 2025-07-16
A generalized definition of derivative that works on manifolds.
TODO: how does it maintain a single value even across different coordinate charts?
EdX by Ciro Santilli 37 Updated 2025-07-16
As of 2022:
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Fuck that.
Also, they have an ICP.
November 2023 course search:
Udacity by Ciro Santilli 37 Updated 2025-07-16
It is a shame that they refocused to more applied courses. This also highlights their highly "managed" approach to content creation. Their 2022 pitch on front page says it all:
for as few as 10 hours a week, you can get the in-demand skills you need to help land a high-paying tech job
they are focused on the highly paid character of many software engineering jobs.
But one cool point of this website is how they hire tutors to help on the courses. This is a very good thing. It is a fair way of monetizing: e-learning websites must keep content free, only charge for certification.
Linear operator by Ciro Santilli 37 Updated 2025-07-16
We define it as a linear map where the domain is the same as the image, i.e. an endofunction.
Examples:
Solving differential equations was apparently Lie's original motivation for developing Lie groups. It is therefore likely one of the most understandable ways to approach it.
It appears that Lie's goal was to understand when can a differential equation have an explicitly written solution, much like Galois theory had done for algebraic equations. Both approaches use symmetry as the key tool.

There are unlisted articles, also show them or only show them.