Chris Purcell @ccppurcell@mathstodon.xyz

Oh, it seems I missed my mathstodon birthday!

Igor Pak has an interesting take on the Elsevier boycott/status of academic publishing. Instead of boycotting individual publishers, boycott using all official websites: instead use arxiv versions, email authors, etc. He makes the case here: https://igorpak.wordpress.com/2019/03/18/the-status-quo-of-math-publishing/

Here's a question: apparently is open whether or not (eg) 9 appears infinitely often in the decimal represenation of pi. So let's call the ten digits good if they appear infinitely often, bad otherwise. It is obvious that at least two digits are good. Is it known whether at least three digits are good?

This weekend I learned that Lagrange was really Italian, not French as I had been led to believe. He is Giuseppe-Luigi not Joseph-Louis! Lagrange is difficult to say without putting on a French accent though.

The number one use I have for my phone camera is taking photos of whiteboards, but google photos is very disparaging about my work. It is always trying to get me to archive these pictures and "get rid of the clutter". Maybe google's photo recognition (which I can use to search my photos for "whiteboard" pretty reliably for instance) has got so sophisticated that it knows I am barking up the wrong tree!

I remember thinking that learning about mathematicians and about the history of mathematics was more or less a waste of time; since the truth of mathematics is independent of human minds, who cares who discovered it? I still think mathematical truth is independent of human minds but I now realise that the scratches we have made in the surface of mathematics say far more about humans than about the whole of mathematics (almost all of which will remain unexplored by us).

This is inspired by the saying "anyone driving slower than me is an idiot; anyone driving faster than me is a maniac."

Anyone less fit than me is risking their life; anyone more fit than me is wasting their time.

@christianp Hey it totally slipped my mind, but the original reason I was looking up that "Seven trees in one" stuff was because I was looking at your esoterica and thought it would be a good addition! I actually forgot that was the motivation *before* writing the initial toot asking for it, and I hadn't fully twigged that you were behind @esoterica at that point (I just noticed it in local timeline)

Tautological gems of wikipedia: A function of bounded mean oscillation is [a function] whose mean oscillation is bounded. #wikipedia

https://en.wikipedia.org/wiki/Bounded_mean_oscillation

addendum: forgive me if this is wrong, but I am almost certain I have this correct.

One of the steps in the Chudnovsky-Seymour clawfree structure theorem is to prove that a connected clawfree graph containing an induced icosahedron must contain a homogeneous pair of cliques. But you can prove something better: such graphs are exactly the graphs you can get from an icosahedron by expanding some of the vertices into cliques (and adding all edges between adjacent cliques). Recreational question: which other pairs of graphs have this property? I have no idea btw.

I am looking for a paper I once read that was about trees (in graph theory). The idea was something like: All trees can be formed from two trees by adding an edge between them, so let's be silly and say that T=T²+1 or some such. The joke being, that's what a "seventeenth century" mathematician might do (or xth century for suitable x). Then the rest of the paper is a great big "aahhh but actually you can make that rigorous". Any ideas?

I've had conversations with non-mathematicians who think an $n$-dimensional space with $n>4$ (or even 3) is just absurd nonsense. But then I was thinking about stable set polytopes of graphs and graphs with at most 4 vertices are pretty trivial for us...

I have been followed by four bots in quick succession, all of whom are from the same mastodon instance, of which they are the only members... what's going on here?

I wonder what proportion of papers these days are written by authors who used sci-hub, or critically rely on other papers that were. Will/has there come a point where all research owes a debt to Alexandra Elbakyan?

My new department gave me a windows machine. Trying to set up Ubuntu on Windows (eg change the godawful color scheme). Various things involve pasting into vimrc or whatever. But terminal can't access windows clipboard! So: paste into text file in windows system, then move it with bash to the home directory, then vim, yank, :e paste. Ffeww.