automata theory automaton automatic translation machine-aided translation automaton [Grk autómatos ‘self-acting’]

In the broad sense, any concrete machine that can perform independently, e.g. telephones or vending machines. In the narrow sense of automata theory. a mathematical model of concrete machines as information-processing systems which store and process input and provide output. All automata are defined as sets of automata states and transitions between these. More complex automata include a last-in-first-out memory (stack automata) or random access memory (Turing machines). In more recent linguistic research automata play an important role as processing models of language. Thus, regular grammars correspond to the finite state automata and context-free grammars correspond to the ‘push-down automata’ or stack automata, and unrestricted grammars (including, for example, all known transformational grammars) correspond to Turing machines (named after the mathematician A.M.Turing).