Output-Determinacy and Asynchronous Circuit Synthesis

Signal Transition Graphs (STG) are a formalism for the description of asynchronous circuit behaviour. In this paper we propose (and justify) a formal semantics of nondeterministic STGs with dummies and OR-causality. For this, we introduce the concept of output-determinacy, which is a relaxation of determinism, and argue that it is reasonable and useful in the speed-independent context. With our theory we improve an STG decomposition algorithm, which can alleviate state explosion.