Things I Said in Class

Students have quietly recorded various things I have said in class, and then they pop up on a public website.

• "I don't understand people who just go into a subway station and get into a random car. I always optimize for travel time. It's great -- I meet my friends on the subway, because they all do the same thing."

• "If you ever encounter a textbook on discrete math that doesn't count the exterior face of a graph when counting faces, burn the book. Then, capture the author and burn him too."

• "When I say a baby-level proof, that's just how mathematicians talk. I don't actually know any babies that can do algebraic topology."

• "Negativebplusorminusthesquarerootofbsquaredminusfouracovertwoa. You have to say it very quickly or you'll get it wrong."

• "When you don't know what I'm doing [in lecture], you can be pretty sure it's self-parody. I'm not quite sure when this happened, but it was so long ago that I can't turn it off.

• "If I ever fail to overstate the case, please call an ambulance."

• "I often get confused when I try to do several things simultaneously. In fact, I sometimes get confused when I try to do one thing simultaneously."

• "I wish I had a surefire way to avoid writing errors in my coursenotes. I once had a fantasy about inventing a computer language that branches on intent."

• "I have no idea what liquid soap will make your dishes sparkle, but I recommend liquid Joy for making high-quality knotted soap bubbles with interesting mathematical properties."

• "The trouble with computers is that they do exactly what you tell them to do, instead of what you want them to do."

• "If you want to be a trillionaire, you can invent a computer with the instruction branch-on-intent."