This paper considers a T period planning problem for single stage in which a sequence of known demands D1,...,DT must be satisfied. An efficient calculation reducing theorey based on cost-path and a new recurrence relation is developed to find optimal policies. Several regeneration points can easily be obtained by comparing setup cost to holding cost. The authors also prove that the knots of a cost-path satisfy the necessary conditions of the Wagner-Whitin algorithm. The new concept could also be used to eliminate the number of additions in the optimal lot size problem for multi-stage assembly systems.
