Cazzandro @KodeGhinn@qoto.org
Spheniscida
Joined Apr 2022
@phastidio non capisco, sulla sdolcinata immagine dell'Italia abbiamo costruito un impero economico. La gente ci vede cosi', ma d'altra parte, come li vediamo noi i sauditi? E i Francesi? Gli inglesi? Etc... Mi pare che anche lei sia caduto sulla sterile polemica calcistica. Consiglio la visione di Luca della Pixar. Luococomunismo alla massima potenza, ma con un po' di poesia, sdolcinata pure quella
Cazzandro
boosted
So, full text search is now live on mastodon.social and mastodon.online.
It is "opt-in", meaning you need to check the Preferences box to enable your posts to be searchable.
@dpiponi at which point you said meep! meep! and ran away in a cloud of dust
@gregeganSF I suppose this is due to the four of "myself" being on the edges of a square so that the diagonal is always through the corner of the L. No matter where I move, I will always look at the "furthest" me across the diagonal. So in this particular case I can identify three black dots that block me looking at myself. But if someone else enters the room I bet the problem becomes more complex
@phastidio potrebbe spiegare la differenza per favore? O indicare una risorsa (link) dove trovare qualche info?
@gregeganSF In my room I have a L-shaped mirror (the doors of a wardrobe). I can see the reflections in front and beside me. But there is a third one which no matter where I move, is stuck in the corner and always cut in two parts between the two sides.
Cazzandro
boosted
The English language is a wonderful thing, and we know some rules without knowing we know them.
‘Have you ever heard that patter-pitter of tiny feet? Or the dong-ding of a bell? Or hop-hip music? That’s because, when you repeat a word with a different vowel, the order is always I A O. Bish bash bosh. So politicians may flip-flop, but they can never flop-flip. It’s tit-for-tat, never tat-for-tit. This is called ablaut reduplication, and if you do things any other way, they sound very, very odd indeed.’ From ‘The Elements of Eloquence’ by Mark Forsyth.
@johncarlosbaez @dpiponi @theohonohan another of the many things Mastodon needs fixing
@dpiponi @theohonohan what do you mean with “locks out”? Does it actually blocks ppl from reading your post? From all other servers or does it just depends on servers?
Scientists at #Fermilab close in on #fifthforce of nature #muons
Cazzandro
boosted
In 2017, I managed to solve a problem from the “Lviv Scottish book” in https://mathoverflow.net/a/282290/766 . The problem had a prize of “butelka miodu pitnego" (a bottle of honey mead). Today, while I was in Warsaw, some representatives from Lviv, Ukraine came (by train, as the Ukraine airspace is obviously closed) I was very touched and honored to unexpectedly receive the prize in person.
Cazzandro
boosted
Suppose you were trying to invent a bright orange powder that could easily dye clothes and be hard to wash off. Using your knowledge of quantum mechanics you'd design this symmetrical molecule where an electron's wavefunction can vibrate back and forth along a chain of carbons at the frequency of green light. Absorbing green light makes it look orange! And this molecule doesn't dissolve in water.
Yes: you'd invent turmeric!
Or more precisely 'curcurmin', the molecule that gives turmeric its special properties.
The black atoms are carbons, the white are hydrogens and the red are oxygens.
Read on and check out what pure curcurmin looks like.
(1/n)
@jwz agreed. But the picture you used is not a mastodon skull ini?
spoiler
@j_bertolotti @johncarlosbaez @RobJLow but this also mean that after infinite time, at some point the ball will start to move infinitesimally slow and than accelerate. And finally slide down the hill and far away
Cazzandro
boosted
One way to view automatic differentiation is to think of it as adjoining an "infinitesimal" element d, such that d²=0, to the reals, ie. forming ℝ[d]/(d²). If f is a polynomial then f(x+d)=f(x)+df'(x) giving a nice way to compute derivatives on a computer - especially as it can be extended to rational and even transcendental functions f. It doesn't form a field though. For example you can't always divide by d.
TIL There is a field, named after Levi-Civita, that generalises ℝ[d]/(d²) quite a bit.
Each element is a "formal" sum ∑aᵢεⁱ where the sum is over some subset S of the rationals which is left-finite, ie. for any z, S has only finitely many elements less than z. Addition and multiplication work in the way you might guess.
This means we can form things like ε^(1/2) or even the "infinite" 1/ε. It's not just a field, it's an ordered field so we have, for example, that 1 > ε^(1/2) > ε > ε² > 0.
You can even construct a Dirac delta-like function δ(x) = ε/π(x²+ε²).
