A world-famous mathematician explores Moore's theory of experiments, Kleene's theory of regular events and expressions, Kleene algebras, the differential calculus of events, factors and the factor matrix, and the theory of operators. Additional subjects include context-free languages, communicative regular algebra, axiomatic questions, and logical problems. Solutions to problems. 1971 edition.
Mathematically sound, but not much use to someone who is actually writing a compiler. His idea that context free languages are better studied as infinite unions of regular expressions is ridiculous. Equally pointless is his idea of an infinite state machine. The example he uses is a language that CAN be written as a single regular expression, which is certainly NOT the case in general.