A complete 4-parametric complexity classification of short shop scheduling problems

We present a comprehensive complexity analysis of classical shop scheduling problems subject to various combinations of constraints imposed on the processing times of operations, the maximum number of operations per job, the upper bound on schedule length, and the problem type (taking values "open shop," "job shop," "mixed shop"). It is shown that in the infinite class of such problems there exists a finite basis system that allows one to easily determine the complexity of any problem in the class. The basis system consists of ten problems, five of which are polynomially solvable, and the other five are NP-complete. (The complexity status of two basis problems was known before, while the status of the other eight is determined in this paper.) Thereby the dichotomy property of that parameterized class of problems is established. Since one of the parameters is the bound on schedule length (and the other two numerical parameters are tightly related to it), our research continues the research line on complexity analysis of short shop scheduling problems initiated for the open shop and job shop problems in the paper by Williamson et al. (Oper. Res. 45(2):288-294, 1997). We improve on some results of that paper. © Springer Science+Business Media, LLC 2011.