Background -- Languages -- Recursive definitions -- Regular expressions -- Finite automata -- Transition graphs -- Kleene's theorem -- Finite automata with output -- Regular languages -- Nonregular languages -- Decidability -- Context-free grammars -- Grammatical format -- Pushdown automata -- DFG = PDA -- Non-context-free languages -- Context-free languages -- Decidability -- Turing machines -- Post machines -- Minsky's theorem -- Variations on the TM -- TM languages -- The Chomsky hierarchy -- Computers.