This paper develops a parts selection model with one-way substitution.
The problem horizon is assumed to be infinite and cost and demand par
ameters are assumed to be stationary over the problem horizon. The obj
ective is to select a subset of parts from the available set of parts
to minimize the average per-period cost. In addition to the purchase a
nd inventory related costs, we assume that there is an overhead cost t
o manage the stock of parts which is a function of the number of parts
kept in stock. The purchase price function used in the paper covers a
ll the commonly used quantity discount models. Several analytical resu
lts are developed for the problem and an efficient dynamic programming
algorithm is developed to find an optimal solution.