Flux qubit Updated 2025-07-16
In Ciro's ASCII art circuit diagram notation, it is a loop with three Josephson junctions:
+----X-----+
|          |
|          |
|          |
+--X----X--+
https://upload.wikimedia.org/wikipedia/en/0/04/Flux_Qubit_-_Holloway.jpg
Video 1.
Superconducting Qubit by NTT SCL (2015)
Source.
Offers an interesting interpretation of superposition in that type of device (TODO precise name, seems to be a flux qubit): current going clockwise or current going counter clockwise at the same time. youtu.be/xjlGL4Mvq7A?t=1348 clarifies that this is just one of the types of qubits, and that it was developed by Hans Mooij et. al., with a proposal in 1999 and experiments in 2000. The other type is dual to this one, and the superposition of the other type is between N and N + 1 copper pairs stored in a box.
Their circuit is a loop with three Josephson junctions, in Ciro's ASCII art circuit diagram notation:
+----X-----+
|          |
|          |
|          |
+--X----X--+
They name the clockwise and counter clockwise states and (named for Left and Right).
When half the magnetic flux quantum is applied as microwaves, this produces the ground state:
where and cancel each other out. And the first excited state is:
Then he mentions that:
  • to go from 0 to 1, they apply the difference in energy
  • if the duration is reduced by half, it creates a superposition of .
Fog computing Updated 2025-07-16
Our definition of fog computing: a system that uses the computational resources of individuals who volunteer their own devices, in which you give each of the volunteers part of a computational problem that you want to solve.
Folding@home and SETI@home are perfect example of that definition.
Formal proof Updated 2025-07-16
A proof in some system for the formalization of mathematics.
Form of government Updated 2025-07-16
Rasselas Prince of Abyssinia CHAPTER VIII www.gutenberg.org/cache/epub/652/pg652-images.html:
Oppression is, in the Abyssinian dominions, neither frequent nor tolerated; but no form of government has been yet discovered by which cruelty can be wholly prevented. Subordination supposes power on one part and subjection on the other; and if power be in the hands of men it will sometimes be abused. The vigilance of the supreme magistrate may do much, but much will still remain undone. He can never know all the crimes that are committed, and can seldom punish all that he knows.
Forsyth-Edwards Notation Updated 2025-07-16
The cool thing about this notation is that is showed to Ciro Santilli that there is more state to a chess game than just the board itself! Notably:
  • whose move it is next
  • castling availability
  • en passant availability
plus some other boring draw rules counters.
Fourier series Updated 2025-07-16
Approximates an original function by sines. If the function is "well behaved enough", the approximation is to arbitrary precision.
Fourier's original motivation, and a key application, is solving partial differential equations with the Fourier series.
The Fourier series behaves really nicely in , where it always exists and converges pointwise to the function: Carleson's theorem.
Video 1.
But what is a Fourier series? by 3Blue1Brown (2019)
Source. Amazing 2D visualization of the decomposition of complex functions.
Fourier transform Updated 2025-07-16
Continuous version of the Fourier series.
Of course, every function defined on a finite line segment (i.e. a compact space).
Therefore, the Fourier transform can be seen as a generalization of the Fourier series that can also decompose functions defined on the entire real line.
As a more concrete example, just like the Fourier series is how you solve the heat equation on a line segment with Dirichlet boundary conditions as shown at: Section "Solving partial differential equations with the Fourier series", the Fourier transform is what you need to solve the problem when the domain is the entire real line.
Fraction Updated 2025-07-16
François and Joseph Blanc Updated 2025-07-16
Very interesting story! A predecessor to microwave transmission for trading.
Video 1.
How The First Ever Telecoms Scam Worked by Tom Scott (2018)
Source. Amazing how they used control signals to hide the information from officials on either side.
Frederick Sanger Updated 2025-07-16
Ah, this seems like a nice dude.
The Eighth Day of Creation has two nice paragraphs about his work. He was shy and quiet, and didn't boast about his slow and steady progress, possibly because of this he only had a junior fellowship and at some point some people wanted to kick him out of the lab somewhere between 1948 - 1952, quoted at: sandwalk.blogspot.com/2013/11/fred-sanger-1918-2013.html
Video 1.
Fred Sanger 1918-2013 by Birgitta Olofsson (2013)
Source. This is a good video especially is you know Cambridge, to help situate Sanger's places a bit. Good Sanger quote at the end:
I always tell people, it is much easier to get the second one than the first
Free and open-source software Updated 2025-07-16
A more precise term for those in the know: open source software that also has a liberal license, for some definition of liberal.
Ciro Santilli defines liberal as: "can be commercialized without paying anything back" (but possibly subject to other restrictions).
He therefore does not consider Creative Commons licenses with NC to be FOSS.
For the newbs, the term open source software is good enough, since most open source software is also FOSS.
But when it's not, it's crucial to know.
Ciro Santilli thinks imperative programming is just a superset of functional programming where you can have state.
C and C++: OK, you're old before the Internet and compiled, forgiven.
Python: OMG, please, just make it work!!! Your are interpreted!!! You are a hot web technology!!! Node.js and Ruby are doing just fine, and Ruby is not newer than you!!! See also: pip.

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