In the study of multiple lot sizing problem with rigid demand, the cost
structure and yield distribution are two main factors to determine the behavior
of such problems. Various yield distributions, such as the binomial, discrete 
uniform, and interrupted geometric yields, all with the linear cost structure, 
are studied in the literature. In this talk, we shall discuss the effects of 
general cost structures with the interrupted geometric yield. We present results
characterizing the behavior of the optimal total cost function and optimal lot 
sizes. In particular, we present results of the lot sizes which hold for the 
linear cost structure but may fail in the framework of a general cost structure.