Show newer
Cazzandro boosted

Today at 3 pm UK time I'm giving a quick intro to n-categories. You can join us online here:

ed-ac-uk.zoom.us/j/82270325098
Meeting ID: 822 7032 5098
Passcode: XXXXXX36

Here the X’s stand for the name of that famous lemma in category theory.

With luck I'll be able to put my talk on YouTube later.

Here's what I'll explain:

An n-category is a gadget with objects, morphisms between objects, 2-morphisms between morphisms, and so on up to n-morphisms. The 'periodic table of n-categories' shows the pattern you get if you look at (n+k)-categories that are boring at the bottom k levels, with just one object, one morphism, and so on for a while. You can think of these as n-categories with k ways to multiply objects. The Stabilization Hypothesis claims that once k reaches n+2, increasing it more has no effect!

Cazzandro boosted

I'm giving a public talk next week:

• Life's struggle to survive. Tuesday September 26, 6 pm UK time. Room G.03 on the ground floor of the Bayes Centre, 47 Potterrow, Edinburgh.

When pondering our future amid global warming, it is worth remembering how we got here. Even after it got started, the success of life on Earth was not a foregone conclusion! In this talk I recount some thrilling, chilling episodes from the history of our planet. For example: our collision with the planet Theia, the "snowball Earth events" when most of the oceans froze over, and the asteroid impact that ended the age of dinosaurs. Some are well-documented, others only theorized, but pondering them may give us some optimism about the ability of life to survive crises.

To attend in person, get a free ticket here: eventbrite.co.uk/e/lifes-strug

Refreshments will be served after the lecture. If you actually show up, say hi!

If you can't join us, fear not: I should be able to put a recording of the talk on my YouTube channel eventually. And you can see the slides here now:

math.ucr.edu/home/baez/struggl

If you find mistakes in them or just have questions, please let me know! I'm still polishing the slides - and the more questions I field now, the more prepared I'll be when it comes time to give the actual talk.

Cazzandro boosted

A few weeks ago I made up a "fake prime function" to illustrate that a certain property wasn't really a property specific to primes. I notice @johndcook wrote about it a couple of times

johndcook.com/blog/2023/08/21/

mathstodon.xyz/@johndcook/1109

In the back of my mind was Cramer's "model" of the primes although I was interested in different statistical properties terrytao.wordpress.com/tag/cra

@phastidio “Dittatura e religione fanno l’orgia sul balcone” - Litfiba

@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.

#English #language

@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?

Show older
Qoto Mastodon

QOTO: Question Others to Teach Ourselves
An inclusive, Academic Freedom, instance
All cultures welcome.
Hate speech and harassment strictly forbidden.