rnather @rnather@mathstodon.xyz

Q: What do you get when you cross a mosquito with a mountaineer? A: Nothing - you can't cross a vector with a scalar.

Someone I know wants to try out Mastodon, but he doesn't know English. Is there:

A) A way to look for users speaking a particular language?

B) A Polish instance that's well moderated (no bigotry allowed on there)?

Please boost, even if you don't know 😓

#mastodon #help

Work-life balance

Assigning students to photograph instances of different frieze pattern symmetry types in real life has been one of the more rewarding problems for me, as a grader, recently.

#Introduction Hello, I am Florian, aspiring model theorist and geometer and not quite a PhD student yet, but I am doing my best to become one soon.

Scientists Uncover the Universal Geometry of Geology (Quanta): https://www.quantamagazine.org/geometry-reveals-how-the-world-is-assembled-from-cubes-20201119/

This is all a bit mystic and breathless and woo, but what it really seems to boil down to is that if you subdivide space by randomly recursively splitting by planes (like a 3d Gilbert tessellation, https://en.wikipedia.org/wiki/Gilbert_tessellation) then the average number of sides per bottom-level polyhedron is six.

Dogs play the game where you don't let the balloon touch the ground. On a beach. I watched at least a dozen loops already and I'm not even close to done

One of my most productive days was throwing away 1000 lines of code. -- Ken Thompson

Origami Fibonacci torus and knotted torus: https://www.youtube.com/watch?v=LdnvxN4UUfs

I have the impression that the Fibonacci part just gives it a nice organic look (visible in much of Akio Hizume's other architecture at http://www.starcage.org/englishindex.html) but what interests me is the way it rotates smoothly. That's not something unfolded paper can do, because the inner parts of a torus have negative curvature, the outer parts are positive, and unfolded paper can't change curvature.

An archive of optical/mechanical/automated drawing machines/devices/aids: https://drawingmachines.org/, via https://news.ycombinator.com/item?id=25033793

Build a man a fire, he's warm for one night. Set him on fire, and he's warm for the rest of his life. -- Terry Pratchett, Jingo

Wonderful mathematical reading:
https://imaginary.org/texts

"Here you can find a variety of mathematical texts on many different topics. One section is related to the “snapshots of modern mathematics from Oberwolfach”, the other section offers general background material connected to our exhibits and projects. We hope you enjoy your read!"

A, C, and E walked into a bar. The bartender said 'Sorry, but I can't serve A minor.'

When people tell you something's wrong or doesn't work for them, they are almost always right. When they tell you exactly what they think is wrong and how to fix it, they are almost always wrong. -- Neil Gaiman

they may be running "Linux", a known communist operating system that's handed out to everyone free of charge (imagine!) and comes with the built in commands "cp" (Communist Party), "ls" (Left Socialism), "rm" (Revolutionary Marxism), and "cat" (Communism at All Times)

Tom Lehrer has released his songs and lyrics into the public domain.

https://tomlehrersongs.com/

What a nice thing to do.

Maybe it's time to update my #introductions pinned toot...

Hey there! I'm a #maths MSc student at University of Helsinki, Finland. I'm specializing in #stochastics, doing quite a bit of analysis alongside. I also sometimes blog about fun maths in Finnish, at www.nollakohta.fi.

I've been a hobbyist programmer for like 2/3 of my life, presently interested in #compilers. In addition to computer languages, you can reach me in Finnish, English, Swedish and French.

A problem of mine appears in the most recent Mathematical Gazette:
"Two unit squares are drawn in the plane with their edges parallel to the coordinate axes and their centres chosen randomly and independently in the region \(-1 \le x,y \le 1\). Determine the expected value for the area of their intersection."

fucked up how there's no uppercase version of the @ sign
(wait would that just be Ⓐ?)

Computer Scientists Break Traveling Salesperson Record: https://www.quantamagazine.org/computer-scientists-break-traveling-salesperson-record-20201008/

I linked to this back in July (https://mathstodon.xyz/@11011110/104465689831962167) when Karlin, Klein, and Gharan's preprint https://arxiv.org/abs/2007.01409 giving a \((3/2-\varepsilon)\)-approximation to TSP first came out, but now it's getting wider publicity in _Quanta_.

See also an earlier (paywalled) piece on the same story in ScienceNews: https://www.sciencenews.org/article/shayan-oveis-gharan-theoretical-computer-scientist-sn-10-scientists-watch