Classes today were Ramsey Theory (still awesome) and the first day of branching processes.

The latter was actually basically an introduction to probability theory (sigma algebras and such). It was well-done, which was nice because the first time I’d seen it at Princeton, when shopping classes, I dropped the class after one day and forgot, and the second time the professor was bad. (When, after several similar incidents, he tried to write out “the set of functions from X to Y” and ended up with “{f(x): x \in X}”, I left partway through class and dropped the course).

Problem session was percolation. Most of the class hadn’t done most of the problems, so we talked about the ones people had done, and then Béla Bollobás improvised and lectured a bit.