Pareto simulated annealing and colonial competitive algorithm to solve an offline scheduling problem with rejection

The present paper considers the problem of scheduling a set of jobs where some jobs may be rejected. The objective function consists of minimizing two criteria simultaneously: the sum of the weighted completion times of the accepted jobs and the sum of the rejection costs. Although the characteristics of this problem have been discussed in the literature, no solution algorithm has yet been proposed. Herein, solution algorithms are developed using two meta-heuristic methods: Pareto simulated annealing (PSA), a multiple-objective optimization approach; and colonial competitive algorithm (CCA), a novel method which is adopted for the first time in a discrete multiple-objective optimization problem. Computational testing illustrates the practicality of both algorithms to find a good estimation of the Pareto optimal set. The quality of the proposed algorithms are evaluated and compared by some available performance measures and a new measure introduced in the paper. The comparative results show that CCA offers better estimation of the Pareto optimal set than PSA.