“…Random quantities in this paper will be in boldface. Let x(t) c R be the inventory of the part being produced at time t; c + and cdenote the surplus and shortage costs per unit of production per unit time, respectively; and x + (t) = max(x (t), 0) and x-(t) = max(-x(t), 0) the corresponding levels of inventory surplus and shortage at time t. An objective function to be minimized, for example, is mrin E{ liri ,c++(t) + c--(t)dt} (1) subject to d+x (t) = u(t) -d, x (0) = 0, where d is a constant demand. The inventory level is random due to the random production rates u(t) that depend on the random failure and repair times.…”