It has been previously shown that for sufficiently large pools of patient-donor pairs, (almost) efficient kidney exchange can be achieved by using at most 3-way cycles, i.e. by using cycles among no more than 3 patient-donor pairs. However, as kidney exchange has grown in practice, cycles among...

We find necessary and sufficient conditions for the stability of all work-conserving policies for multiclass fluid queuing networks with two stations. Furthermore, we find new sufficient conditions for the stability of multiclass queuing networks involving any number of stations and conjecture...