Linear dynamic Kahn networks are deterministic

Abstract

The (first part of the) Kahn principle states that networks with deterministic nodes are deterministic on the I/O level: for each network, different executions provided with the same input streams deliver the same output streams. The Kahn principle has thus far not been proved for dynamic, nondeterministic networks. We consider a simple language L containing the fork-statement. For this language we introduce a nondeterministic transition system which defines all interleavings consisting of basic steps, for all possible executions of a program. We prove that, although on the execution level there is much nondeterminism, this nondeterminism disappears because all executions deliver the same output stream (or a prefix of it), given the same input stream. This proves the Kahn principle for linear, nondeterministic dynamic networks.