Automata circuits and mappings realized by them

The paper is concerned with the use of deterministic vocabulary mappings (DVM) which may be specified by feedback circuits. Each circuit is described by an automaton of special kind, the so-called circuit automaton. Circuit automata are referred to as circuit equivalent if they specify the same DVM transformation. The kind of transformations which can be specified by circuit automata is found. An algorithm for checking circuit equivalence of the automata and one for minimizing the number of feedbacks in the circuit which specifies the given DVM transformation are described.