Consider the Economic Lot Size Model and let K be the set-up cost, h be
the holding cost per item per unit of time and D the demand rate.
Shortage is not allowed and the objective is to find an order quantity
so as to minimize the long-run average cost. That is, the objective is
to minimize
where Q is the order quantity. Suppose the warehouse can order only an
integer multiple of q units. That is, the warehouse can order q, or 2q,
or 3q, etc.
Prove that the optimal order quantity Q* has the following property.
There exists an integer m such that Q* = mq and
,
where Qe, the Economic Order Quantity, is:
