[tel]

I’m not a huge fan of these, but this time I noticed that the best ones feel a lot like naturality arguments. As in, moving structural bits in a way that makes it clear that we’re not touching anything that ought to be universally quantifiable.

I still don’t love this sort of thing being presented as “proof”, but I thought that idea is interesting. Is there a way to formalize naturality into technical diagrams? Probably!