You disagree with what? I never said anything about practical applications. And you'd better bet that complexity theory (and the world of topics that basic fami

You disagree with what? I never said anything about practical applications. And you'd better bet that complexity theory (and the world of topics that basic familiarity with complexity theory opens) has more important applications. Cryptography, combinatorial optimization, approximation algorithms, communication complexity, machine learning theory, need I go on? All I'm saying is that automata theory doesn't give the glimpse into theoretical computer science that every "introductory theory" textbook ought to.