Greedy Heuristic and Genetic Algorithms for the Multi-resource Shop Scheduling with Resource Flexibility

This paper deals with the scheduling problem of multi-resource job shop with resource flexibility. In such a problem, each operation may need a combination of more than one resource to be performed and there may be several possible resource combinations for each operation. The scheduling problem consists in both assigning the resources to operations and sequencing the operations on the chosen resources. A polynomial algorithm for solving a particular case with two jobs is proposed, and the notion of the combined job is introduced. Based on these results, a greedy algorithm that considers jobs one after another according to an initial job sequence is developed for dealing with the general case with more than two jobs. The greedy algorithm is guided by a genetic algorithm in order to explore interesting job sequence. Numerical results are given on some existing benchmarks.