Classification of 4-transitive groups Updated 2025-07-16
en.wikipedia.org/w/index.php?title=Mathieu_group&oldid=1034060469#Multiply_transitive_groups is a nice characterization of 4 of the Mathieu groups.
Classical mechanics Updated 2025-07-16
Classical limit Updated 2025-07-16
The idea tha taking the limit of the non-classical theories for certain parameters (relativity and quantum mechanics) should lead to the classical theory.
It appears that classical limit is only very strict for relativity. For quantum mechanics it is much more hand-wavy thing. See also: Subtle is the Lord by Abraham Pais (1982) page 55.
Ciro's call hierarchy notation Updated 2025-07-16
This is a simple hierarchical plaintext notation Ciro Santilli created to explain programs to himself.
It is usuall created by doing searches in an IDE, and then manually selecting the information of interest.
It attempts to capture intuitive information not only of the call graph itself, including callbacks, but of when things get called or not, by the addition of some context code.
For example, consider the following pseudocode:Supose that we are interested in determining what calls
f1() {
}
f2(i) {
if (i > 5) {
f1()
}
}
f3() {
f1()
f2_2()
}
f2_2() {
for (i = 0; i < 10; i++) {
f2(i)
}
}
main() {
f2_2()
f3()
}f1.Then a reasonable call hierarchy for
f1 would be:f2(i)
if (i > 5) {
f1()
f2_2()
for (i = 0; i < 10; i++) {
f2(i)
main
f3
f3()
main()Some general principles:
Ciro Santilli's undergrad studies at the University of São Paulo Updated 2025-07-16
Ciro's official diploma from the University of São Paulo read "Automation and Control Engineer at the Polytechnic School of the University of São Paulo".
The University of São Paulo had been elected the best South American university in the Times Ranking 2013 (archive) in all subjects.
Ciro finished the course with honors of "The Best Student in Automation and Control of the year 2013".
Ciro didn´t learn basically any control engineering however unfortunately. He did only the 3 base years of the electrical engineering course, and the rest got lost on stupid politics of having to go back to do 6 months from France to validate his Brazilian degree, see also: Section "Don't force international exchange students to come back early".
Hazard (computer architecture) Updated 2025-07-16
Ciro Santilli's legs sometimes itch when he runs Updated 2025-07-16
Ciro Santilli has an undiagnozed condition where his upper legs and lower torso often start to itch when he runs, to the point of being extremely annoying and removing all pleasure form the activity.
If some doctor knows why this could be, please tell him!!!
The problem is a bit hard to reproduce however, and Ciro hasn't been able to determine which exact condition triggers it: temperature, nutrition, something else?
Ciro believes that this is not chiefly due to transpiration, but rather to the impact motion that running does on the muscles, as he has felt something similar on his arms some times while cycling in very rough terrain, which made his arms shake in a similar fashion. or for example if he has a water bottle on a tightly tied backpack that rubs his back, then the back itches at that point.
Also, running on a threadmill is not a problem at all. Ciro believes that this is because the threadmill is better amortized, and therefore does not cause the same mechanical stress required to create the itching as running on pavement.
Interestingly, Ciro didn't feel that at all when he played soccer enthusiastically as a child, and he was one of the fastest runners of the group for sure at that time. So he's not sure if it started when he got older, or if it is just because the difference in workloads between soccer and running.
youtu.be/PNgYW5N95z8?t=945 "My back itches" after riding on a bumpy makeshift motorcycle.
Ciro Santilli's hardware TP Link ARCHER VR2800 Updated 2025-07-16
Manual: www.tp-link.com/uk/support/download/archer-vr2800/ In particular, the user guide: static.tp-link.com/1910012125_Archer%20VR2800(EU)_V1_UG.pdf
Admin IP address: 192.168.1.1/ It also works over Wifi and people don't know how to disable that: community.tp-link.com/en/home/forum/topic/1460
Guqin player Updated 2025-07-16
Business film Updated 2025-07-16
Ciro Santilli defines a "business film" as a film about business, enterprises or entrepreneurship. Political thrillers are closed related as well.
This is one of his favorite film genres!
Some lists:
- www.99signals.com/movies-entrepreneur-watch-inspiration Hit and miss.
- www.imdb.com/list/ls033563570/ Best Business Movies and Documentaries by scott_dowle
Quantum number Updated 2025-07-16
Quantum numbers appear directly in the Schrödinger equation solution for the hydrogen atom.
However, it very cool that they are actually discovered before the Schrödinger equation, and are present in the Bohr model (principal quantum number) and the Bohr-Sommerfeld model (azimuthal quantum number and magnetic quantum number) of the atom. This must be because they observed direct effects of those numbers in some experiments. TODO which experiments.
E.g. The Quantum Story by Jim Baggott (2011) page 34 mentions:This refers to forbidden mechanism. TODO concrete example, ideally the first one to be noticed. How can you notice this if the energy depends only on the principal quantum number?
As the various lines in the spectrum were identified with different quantum jumps between different orbits, it was soon discovered that not all the possible jumps were appearing. Some lines were missing. For some reason certain jumps were forbidden. An elaborate scheme of ‘selection rules’ was established by Bohr and Sommerfeld to account for those jumps that were allowed and those that were forbidden.
Quantum Numbers, Atomic Orbitals, and Electron configurations by Professor Dave Explains (2015)
Source. He does not say the key words "Eigenvalues of the Schrödinger equation" (Which solve it), but the summary of results is good enough. Ciro Santilli's hardware Skullcandy Smokin' Buds 2 Updated 2025-07-16
2023-07: one of the sides broke near center, rebuying.
2021-07: wire half broke near connector, only works in some positions. The funny thing is: only voices seem to be blocked out! Rebuying.
2021-06: a small bottom piece of the left earpiece broke. Wire seems find, that is like a little extension to protect wire. Let's see for how long.
2020-20: wires at one of ears broke, not sure how.
Look they looked exactly like: "Skullcandy Smokin' Buds 2 In-Ear Audio Earbud Headphones with In-Line Microphone - Black".
Re-buying that one 10 pounds:
Tech specs:
Connection Type: 3.5mm AUX CableImpedence: 32 ohmsDriver Diameter: 9mmSound Pressure Level: 95 dB (1mW/500Hz)Frequency Response: 20kHz - 20HzHeadphone Type: In-Ear
BookofProofs Updated 2025-07-16
No open signup it seems. TODO CV of owner.
They are making a proof assistant to integrate into the website: github.com/bookofproofs/fpl/, reminds Ciro Santilli of website front-end for a mathematical formal proof system.
Boosted fission weapon Updated 2025-07-16
Born-Oppenheimer approximation Updated 2025-07-16
Bose-Einstein condensate Updated 2025-07-16
Inward Bound by Abraham Pais (1988) page 282 shows how this can be generalized from the Maxwell-Boltzmann distribution
Boston Marathon bombing Updated 2025-07-16
Bounding box Updated 2025-07-16
Bo Ya Updated 2025-07-16
en.wikipedia.org/w/index.php?title=Bo_Ya&oldid=1150295883#The_story_about_Zhiyin:
Bo Ya was good at playing the qin. Zhong Ziqi was good at listening to the qin. When Bo Ya's will was towards high mountains in his playing, Zhong Ziqi would say, "How towering like Mount Tai!" When Bo Ya's will was towards flowing water in his playing, Zhong Ziqi would say, "How vast are the rivers and oceans!" Whatever Bo Ya thought of Ziqi would never fail to understand. Bo Ya said, "Amazing! Your heart and mine are the same!" After Zhong Ziqi died, Bo Ya broke his Guqin because he thought that no one else can understand his music.
Linear map Updated 2025-07-16
One thing that makes such functions particularly simple is that they can be fully specified by specifyin how they act on all possible combinations of input basis vectors: they are therefore specified by only a finite number of elements of .
Every linear map in finite dimension can be represented by a matrix, the points of the domain being represented as vectors.
As such, when we say "linear map", we can think of a generalization of matrix multiplication that makes sense in infinite dimensional spaces like Hilbert spaces, since calling such infinite dimensional maps "matrices" is stretching it a bit, since we would need to specify infinitely many rows and columns.
The prototypical building block of infinite dimensional linear map is the derivative. In that case, the vectors being operated upon are functions, which cannot therefore be specified by a finite number of parameters, e.g.
For example, the left side of the time-independent Schrödinger equation is a linear map. And the time-independent Schrödinger equation can be seen as a eigenvalue problem.
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