Tomorrow (July 25, 2020), at 8 am Pacific, the fifth pseudolecture will take place, in the same way as the previous one(s).  If you need more instructions, just comment below, or ask on discord or zulip!  (I’m not sure if this announcement is needed, but to be safe, I’m posting it…)

And just to give this post some more interesting content, at the Algebraic Geometry Syndicate earlier this week, James Grant pointed out that

Richard E. Borcherds has posted three series of lectures regarding algebraic geometry. These are quite good, in my opinion.

I’ve dipped into them briefly (as I just saw this), and agree!  Here’s the link.

Also, Juliette Bruce had something to add as to why \mathcal{O}  is used for sheaves of functions (taken from her comments on zulip).

Some people think the symbol \mathcal{O} was chosen in honor of Oka, sometimes it is even said that \mathcal{O} reflects the French pronunciation of holomorphe. The truth is that the symbol was chosen accidentally.  In a letter to the authors from March 22, 1982, H. Cartan writes: “Je m’étais simplement inspiré d’une notation utilisée par van der Waerden dans son classique traité ‘Moderne Algebra’ (cf. par exemple §16 de la 2e édition allemande, p.52) [I was simply inspired by a notation used by van der Waerden in his classical treastise `Modern Algebra’…”

Link here.

Further digging from Keith Conrad seems to suggestion van der Waerden’s book was based on lectures by Emmy Noether, and the notation likes originates from Dedekind to use of \mathfrak{O} for an order (Ordnung in German).

Link here.