A polynomial-time algorithm for checking consistency of free-choice signal transition graphs

Signal Transition Graphs (STGs) are one of the most popular models for the specification of asynchronous circuits. A STG can be implemented if it admits a so-called consistent and complete binary encoding. Deciding this is EXPSPACE-hard for arbitrary STGs, and so a lot of attention has been devoted to the subclass of free-choice STGs, which offers a good compromise between expressive power and analizability. In the last years, polynomial time synthesis techniques have been developed for free-choice STGs, but they assume that the STG has a consistent binary encoding. This paper presents the first polynomial algorithm for checking consistency.