In this paper a new mixed integer programming (MIP) model formulation and its incorporation into a time-oriented decomposition heuristic for the capacitated lot-sizing problem with linked lot sizes (CLSPL) is proposed. The solution approach is based on an extended model formulation and valid inequalities to yield a tight formulation. Extensive computational tests prove the capability of this approach and show a superior solution quality with respect to other solution algorithms published so far.Lot-Sizing, MIP, Valid Inequalities, CLSPL

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The planning and scheduling of chemical plants still leaves several opportunities for optimization. Therefore, many authors have made contributions to this field, resulting in generally two modeling paradigms: continuous time and discrete time model formulations. As both modeling approaches have their advantages, the model formulation presented here is based on a discrete time scale while, at the same time, taking aspects of time continuity into account. It is shown that the proposed modeling approach compares favorably with three model formulations from the literature. Furthermore, a closer evaluation shows that all these benchmarks suffer from minor flaws.

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