Abstract :
A generalized model of automata is defined in which the outputs are sequences of letters (rather than single letters) for each input letter. The output sequences are transmitted without spacing, just as in the case of variable length codes. The paper describes a test for determining whether a given generalized automaton is information lossless, and if so, whether information lossless of finite order. (Decipherable with finite delay.) The codes generated by generalized automata are believed to be even harder to break than ordinary variable length codes. The techniques described in the present paper provide useful tools in the design of such coding procedures.
