I. Introduction
State encoding is one of the critical problems during the synthesis of asynchronous control circuits. Several methods have been proposed in the past, either for circuits working in fundamental mode [1] or input/output mode [2], among others. In the latter case, the concurrency between input and output events imposes more severe constraints on the insertion of internal signals to disambiguate encoding conflicts. What makes encoding difficult is the preservation of the implementability properties of the specification (e.g., consistency and persistence) after the insertion of new events.