Skip to content

Young Diagrams and Classical Groups [pdf]

math.ucr.edu
37 pointsg0xA52A2A7 comments
On HN

Comments

The underlying idea is the idea of fixed points (aka spectra, diagonalizations, embedding, invariants, braids). By fixed point I mean something like the "Lawvere's fixed point theorem". https://ncatlab.org/nlab/show/Lawvere%27s+fixed+point+theore...

I have a linkdump on this

https://github.com/adamnemecek/adjoint

I also have a discord https://discord.gg/mr9TAhpyBW

The only two 1-dimensional representations of the symmetric group (i.e., what you can call fixed points if you squint a bit) are the ones that correspond to the partitions (n) and (1,1,...,1), which are the least interesting ones. Everything else is significantly more complicated. It's a block-diagonalization (Young seminormal form) with lots of nontrivial blocks. So no, you won't understand it in terms of fixed points (and certainly not of Lawvere's theorem, which I've never seen used in the entire subject).

What's the discord for?

Further discussion.

About what specifically

I knew Craige Schensted left his mark on the subject; I had no idea his wife (Irene Verona Schensted) had written a book about it! (well, I think it's about it; it's not on libgen...)

Awesome! Thank you!

AboutSource Built by g1lg1l

Hackerly is an independent reader for Hacker News, built on the public HN API. Not affiliated with Y Combinator.