  Equilibrium G/M/1-FIFO waiting times are exponentially distributed, as first
proved by Smith (1953). For other client-sorting policies, such generality is
not feasible. Assume that interarrival times are constant. Symbolics for the
D/M/1-LIFO density are completely known; numerics for D/M/1-SIRO arise via an
unpublished recursion due to Burke (1967). Consider a weighted sum of two
costs, one from keeping clients waiting for treatment and the other from having
the server idle. With this in mind, what is the optimal interarrival time and
how does this depend on the choice of policy?
