This paper deals with proportional lot sizing and scheduling (PLSP) and gives some insights into the properties of this problem. Such insights may be useful for developing heuristic and/or exact solution procedures. The emphasis of this paper is on the multi-level, multi-machine case. We provide...

This contribution generalizes the work of Drexl and Haase about the so-called proportional lot sizing and scheduling problem which was published in 1995. While the early paper considers single-level cases only, the paper at hand describes multi-level problems. 1t provides mixed-integer programs...

This contribution defines an instance generator for capacitated, dynamic, multi-level lot sizing problems. It provides sophisticated methods for generating systematically varied parameter level combinations automatically. This helps to perform evaluations of lot sizing methods according to a...

Where standard MLP-solvers fail to compute optimum objective function values for certain MLP-model formulations, lower bounds may be used as a point of reference for evaluating heuristics. In this paper, we compute lower bounds for the multi-level proportional lot sizing and scheduling problem...

This contribution introduces a mixed-integer programming formulation for the multi-level, multi-machine proportional lot sizing and scheduling problem. It also presents a genetic algorithm to solve that problem. The efficiency of that algorithm is due to an encoding of solutions which uses a...

A flow line consists of a sequence of work places (or stations) through which one or more producta (or models) move one-way in order to be processed. Each model requires specific Operations which must be performed in a predefined Order. To be able to do so, the stations must be equipped with...

While balancing straight assembly lines is a well-studied problem, the Situation where the assembly line has a U-shaped Iayout is a still emerging research field. The advantage of these lines is that workers may simply turn around to operate at two legs of the line. Hence, there is an additional...

This paper presents a mixed-integer program for the dynamic lot sizing and scheduling problem in a multi-level, single-machine environment. It turns out that in contrast to single-level problems the integration of initial inventory is a crucial aspect if generality should not be lost. It is...