Sorbonne University Updated +Created
Lebesgue integral vs Riemann integral Updated +Created
Advantages over Riemann:
Video 1.
Riemann integral vs. Lebesgue integral by The Bright Side Of Mathematics (2018)
Source.
youtube.com/watch?v=PGPZ0P1PJfw&t=808 shows how Lebesgue can be visualized as a partition of the function range instead of domain, and then you just have to be able to measure the size of pre-images.
One advantage of that is that the range is always one dimensional.
But the main advantage is that having infinitely many discontinuities does not matter.
Infinitely many discontinuities can make the Riemann partitioning diverge.
But in Lebesgue, you are instead measuring the size of preimage, and to fit infinitely many discontinuities in a finite domain, the size of this preimage is going to be zero.
So then the question becomes more of "how to define the measure of a subset of the domain".
Which is why we then fall into measure theory!
LGM-30 Minuteman Updated +Created
Ah, the choice of name, both grim and slightly funny, Dr. Strangelove comes to mind quite strongly. Also Fallout (franchise).
Video 1.
The $130B Plan to Replace the U.S.’s Nuclear Missiles by The Wall Street Journal
. Source.
https://web.archive.org/web/20230321151835im_/https://minutemanmissile.com/images/HICSCableCloseUp.jpg
https://web.archive.org/web/20230321151835im_/https://minutemanmissile.com/images/HICSCableSplicerTwo.jpg
https://web.archive.org/web/20230321151835im_/https://minutemanmissile.com/images/HICSCableConnectivitySchematic.jpg
Lie algebra of a matrix Lie group Updated +Created
For this sub-case, we can define the Lie algebra of a Lie group as the set of all matrices such that for all :
If we fix a given and vary , we obtain a subgroup of . This type of subgroup is known as a one parameter subgroup.
The immediate question is then if every element of can be reached in a unique way (i.e. is the exponential map a bijection). By looking at the matrix logarithm however we conclude that this is not the case for real matrices, but it is for complex matrices.
TODO example it can be seen that the Lie algebra is not closed matrix multiplication, even though the corresponding group is by definition. But it is closed under the Lie bracket operation.
List of Nobel Prizes in Chemistry Updated +Created
OpenStax Updated +Created
These people have good intentions.
The problem is that they don't manage to go critical because there's to way for students to create content, everything is manually curated.
You can't even publicly comment on the textbooks. Or at least Ciro Santilli hasn't found a way to do so. There is just a "submit suggestion" box.
This massive lost opportunity is even shown graphically at: cnx.org/about (archive) where there is a clear separation between:
  • "authors", who can create content
  • "students", who can consume content
Maybe this wasn't the case in their legacy website, legacy.cnx.org/content?legacy=true, but not sure, and they are retiring that now.
Thus, OurBigBook.com. License: CC BY! So we could re-use their stuff!
TODO what are the books written in?
Video 1.
Richard Baraniuk on open-source learning by TED (2006)
Source.
China front Updated +Created
I've started rewatching The Water Margin, it is just so good. I'm taking some reasonable notes this time however, because due to Ciro Santilli's bad old event memory I'll forget the details again otherwise.
That type of rebellion symbology could also be useful against the Chinese government. It is interesting that Mao Zedong loved the novel.
Video 1.
Water Margin tribute to Chinese dissidents
. Source.
John Bardeen Updated +Created
Video 1.
The Story of John Bardeen at the University of Illinois (2010)
Source.
kitone/subtitleeditor Updated +Created
Not to be confused with Subtitle Edit.
As of 0.54.0 this feels featureful, but extremely buggy or lacking UI obvious enhancements that would be simple to implement, and offer huge value:
It is hard to understand how that project reached this weird featureful but crappy state. Feels like they just gave push permission to a bunch of random people.
Light cone Updated +Created
A subset of Spacetime diagram.
The key insights that it gives are:
  • future and past are well defined: every reference frame sees your future in your future cone, and your past in your past cone
    Otherwise causality could be violated, and then things would go really bad, you could tell your past self to tell your past self to tell your past self to do something.
    You can only affect the outcome of events in your future cone, and you can only be affected by events in your past cone. You can't travel fast enough to affect.
    Two spacetime events with such fixed causality are called timelike-separated events.
  • every other event (to right and left, known as spacelike-separated events) can be measured to happen before or after your current spacetime event by different observers.
    But that does not violate causality, because you just can't reach those spacetime points anyways to affect them.
Figure 1.
Animation showing how space-separated events can be observed to happen in different orders by observers in different frames of reference
. Source.
Lin Chong scene Updated +Created
Lance instructor of the 800,000 Imperial Guards (八十万禁军枪棒教头). TODO understand the "枪棒" part: zhidao.baidu.com/question/206659649.html.
The adopted son of Gao Qiu wanted to fuck his wife, and because of this they frame him of planning to take revenge by killing Go Qiu, even though Lin Chong had decided not to take revenge to avoid harming his wife further.
They just keep trying to kill him, until at one point he just gives up and becomes a fugitive.
His story is well told in The Water Margin.
Usually called by others as 林教头 (lin jiaotou, literally Head Instructor Lin, but usually translated as just Instructor Lin).
Magazine Updated +Created
Fiat currency Updated +Created
A useless piece of paper (or digital version of it) that you can pay taxes with :)
As opposed to:
  • 2020 cryptocurrencies, while governments still don't accept them for taxes, as well as other assets that are also not accepted for taxes (i.e. most assets)
  • physical currencies that have intrinsic material value, e.g. gold coins
Linear differential equation Updated +Created
The name is a bit obscure if you don't think in very generalized terms right out of the gate. It refers to a linear polynomial of multiple variables, which by definition must have the super simple form of:
and then we just put the unknown and each derivative into that simple polynomial:
except that now the are not just constants, but they can also depend on the argument (but not on or its derivatives).
Explicit solutions exist for the very specific cases of:
Lost Horse LLC Updated +Created
MacKenzie Bezos's charity instrument.
www.irishtimes.com/life-and-style/people/mackenzie-scott-how-the-former-mrs-bezos-became-a-philanthropist-like-no-other-1.4850049 MacKenzie Scott: How the former Mrs Bezos became a philanthropist like no other (2020) has some good mentions:
But as Scott's fame for giving away money has grown, so too has the deluge of appeals for gifts from strangers and old friends alike. That clamour may have driven Scott's already discreet operation further underground, with recent philanthropic announcements akin to sudden lightning bolts for unsuspecting recipients.
The name of the organization is a reference to the old man lost his horse.
Micro Bit example Updated +Created

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