A proof of the Kahn principle for input/output automata

TLDR: The authors use input/output automata to define a simple and general model of networks of concurrently executing, nondeterministic processes that communicate through undirectional, named ports, and it is shown that determinate processes compute continuous functions, and that networks of determinates obey Kahn's fixed-point principle.

Abstract: : The authors use input/output automata to define a simple and general model of networks of concurrently executing, nondeterministic processes that communicate through undirectional, named ports. A notion of the input/output relation computed by a process is defined, and determinate processes are defined to be processes whose input/output relations are single-valued. It is shown that determinate processes compute continuous functions, and that networks of determinate processes obey Kahn's fixed-point principle. Although these results are already known, our contribution lies in the fact that the input/output automata model yields extremely simple proofs of them (the simplest we have seen), in spite of its generality.