Cazzandro @KodeGhinn@qoto.org

Applied Category Theory course by @johncarlosbaez:
https://math.ucr.edu/home/baez/act_course/index.html
Very short, self-contained lessons, great for casual reading with concrete applications!

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

https://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!

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: https://www.eventbrite.co.uk/e/lifes-struggle-to-survive-leverhulme-lecture-tickets-707700620607

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:

http://math.ucr.edu/home/baez/struggle/

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.

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

https://www.johndcook.com/blog/2023/08/21/fake-primes/

https://mathstodon.xyz/@johndcook/110927666845223894

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

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.

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

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.