Neighbourhood Constraint for a Tabu Search Algorithm to Schedule Jobs on Unrelated Parallel Machines

This work deals with the problem of scheduling n independent jobs on m unrelated parallel machines with the objective of minimizing the makespan (the total elapsed time from the start of execution until all jobs have been completed). Preemption is not allowed. This way a job, once assigned to a particular machine, may not be removed until it has finished its execution. All the machines start working on the jobs simultaneously. This problem, according with classification described in [4], can be represented as scheduling problem R || Cmax. The R || Cmax is known to be NP-hard [2, 4], and therefore, very unlikely to find an optimal solution in polinomial time.