Sorting and Election in Anonymous Asynchronous Rings

In an anonymous ring of n processors, all processors are totally indistinguishable except for their input values. These values are not necessarily distinct, i.e., they form a multiset, and this makes many problems particularly difficult. We consider the problem of distributively sorting such a multiset on the ring, and we give a complete characterization of the relationship with the problems of leader election for vertices and edges. For Boolean input values and prime n; we also establish a lower bound, and a reasonably close upper bound on the message complexity valid for sorting and leader election.