Cute proof of Sperner's theorem (https://en.wikipedia.org/wiki/Sperner%27s_theorem) from a talk by R. P. Stanley last Thursday: represent subsets of \([0,n-1]\) by strings of \(n\) parens, ")" in position \(i\) if \(i\) is in the set, "(" otherwise. In each string, flip the first unmatched (, grouping the subsets into chains like (()(( – )()(( – )())( — )())). Each chain touches the middle level once, and any other antichain at most once, so the middle level is the biggest antichain. #proofinatoot
I have £60 of birthday money and I want to spend it on something frivolous and mathematical. Any ideas? #math
I made a new page of sliding block puzzles:
Some great mathematical "colemanballs"
Quit using Mendeley people!
They started encrypting your database so you cannot easily move it over to other tools any more.
That link also helps you saving your data before it's too late.
(Elsevier are a bunch of crooks, blocking interoperability one-way and not the other. Almost as bad as Google blocking uBlock for your safety...)
I've just learned about Grete Hermann, a German mathematician and philosopher, and student of Emmy Noether. She was an anti-fascist, and provided a sort-of constructive solution to Hilbert's Nullstellensatz.
Mathematician, koala fan, mathstodon.xyz admin,
⅓ of https://aperiodical.com
A Mastodon instance for maths people. The kind of people who make \(\pi z^2 \times a\) jokes.
\) for inline LaTeX, and
\] for display mode.