I thought his videos were uncommonly good, and it it turns out he did a PhD in algebraic automata theory or something. My comment : 53:12 This is all new to me. I only heard about algebraic automata theory a month or two ago! But I did hear a notable clip of Hilary Putnam talking about Turing machines having a normal form, which I wasn't aware of. Actually, I am not sure I know what "a normal form" means, but I imagine he was referring to the idea that no matter how many tapes, or how many symbols, or how many state transition tables you have, you can formulate any machine in some arbitrarily chosen "canonical" form, say two symbol alphabet and one infinite tape and one state transition table. I'll try find the clip and post it as a response to this comment, but YouTube will probably delete it, because YouTube is not meant to be used for people to actually communicate ideas or anything, it is meant to make people watch ads. Subscribe to Thomas Kern . 5:25...