I think it's a shame this wasn't highlighted more explicitly in, at least, my computer science degree. We did finite state machines in quite a bit of detail, v

I think it's a shame this wasn't highlighted more explicitly in, at least, my computer science degree. We did finite state machines in quite a bit of detail, vaguely referred to pushdown automata but then concentrated on lambda calculus for quite a lot, with Turing machines less so. The Turing machine description, without showing it in this hierarchy, seems like a really weird abstraction. Fitting it in here (and combining it with the different Chomsky classes of grammar) makes it all feel more joined up.