“…In the context of scheduling and queueing problems, the relevant asymptotic regime is the heavy traffic limit, under which the stochastic model can be approximated by either a diffusion process or an ODE system; the limit models are named Brownian network or fluid approximation, depending on whether the limiting differential equation is stochastic or deterministic. Readers interested in the Brownian network approach may consult [23,42,40,36,37,59] and references therein. For the fluid approximation of stochastic queueing networks, we refer to [12,11,40]; cf.…”