Leader Election in Asymmetric Labeled Unidirectional Rings

We study (deterministic) leader election in unidirectional rings of homonym processes that have no a priori knowledge on the number of processes. In this context, we show that there is no algorithm that solves process-terminating leader election for the class of asymmetric labeled rings. In particular, there is no process-terminating leader election algorithm in rings in which at least one label is unique. However, we show that process-terminating leader election is possible for the subclass of asymmetric rings, where multiplicity is bounded. We confirm this positive results by proposing two algorithms, which achieve the classical trade-off between time and space.