Welcome to class today, I am your instructor, Uluscri. Good to meet you all. I look forward to a productive course.

I hope you all signed the syllabi? I know they were a little big, but that sort of thing is standard around here. Just put them in the crate, and I'll collect them at the end of class.

Okay, I know the break was long, so I think a warm-up is due.

Who's ready for an introductory proof?