Consider again the model in Sect. $4\mathrm{.}4$ without the backorder cost b$1$ per unit

and time unit. Assume now that there is a lower limit for the fill rate, $1$ x$,$

i$.$e$.,$ the fraction of demand that can be satisfied immediately from stock on

hand. Let the constraint be x $<=$ x

$.$ Determine the optimal policy. Compare

with the optimal policy for the original problem.