Simple greedy methods for scheduling hybrid flowshops with due date windows

Abstract

In real life due dates are intervals rather than points in time. In this paper we deal with hybrid flowshops where jobs do not incur in penalties if they are completed inside given due windows. The objective to minimize is the weighted earliness and tardiness from the given due window. We propose simple heuristics based on iterated greedy and iterated local search. We present some procedures: an optimal idle time insertion and a two stage local search which considers a limited local search on a exact representation. We carry out a complete computational experiment, including a reimplementation and comparison of other 9 competing algorithms. A benchmark of more than 3000 instances is used to show that our presented methods are statistically better than existing approaches. Experiments are also conducted to analyze the contribution of each part of the presented procedure.