On finite automata with a time-variant structure

Basic theory of finite automata whose state transitions and outputs depend on time is developed. A necessary and sufficient condition for a language to be accepted by such an automaton is established. Interrelations between various types of time-variant automata, including nondeterministic ones, are studied. Results concerning the closure (under various operations) of the family of languages accepted by time-variant automata are obtained. Finally, time-variant automata are compared with other types of automata