Biconsistency and Homonymy in Distributed Systems with Edge Symmetry

. The unexpected impact that port labeling has on the performance of the overall system has been extensively studied; in particular the focus has been on the choices which yield global consistency properties known as sense of direction. The impact has been documented for a large variety of distributed tasks for a large variety of communication topologies (for a recent survey see [8]). These studies and the evidence they provided have shown the need and importance of understanding the nature of sense of direction and, in general, of labeling consistency. This requires identifying and investigating basic factors, determining their properties, and studying their interaction. In this paper we concentrate on systems with edge symmetry, that is systems where there is a bijection between the port numbers assigned at the two end of a communication link. This is typically the case in communication networks; e.g., the \leftright " labeling in rings, the \compass" (north-south, ea..