A priority based assignment problem

This paper discusses a priority based assignment problem related to an industrial project consisting of a total of n jobs. Depending upon its work breakdown structure, the execution of the project is carried out in two stages where the m primary jobs are performed first, in Stage-I whereas the (n−m) secondary jobs are performed later in Stage-II (as the secondary jobs cannot be performed until the primary jobs are finished). A number of manufacturing units exactly equal to n, each of them capable of performing all the n jobs involved in the project, are available. A tentative job-performance time taken by each of these manufacturing units for each of the n jobs is available. The purpose of the current study is to assign the jobs to the manufacturing units in such a way that the two-stage execution of the project can be carried out in the minimum possible time. For this, a polynomial time iterative algorithm is proposed, which at each iteration, aims at selecting m manufacturing units to perform primary jobs corresponding to which, the remaining (n−m) manufacturing units perform the secondary jobs optimally and from this selection, a pair of times of Stage-I and Stage-II is obtained. The proposed algorithm is such that at each iteration, time of Stage-I decreases strictly and time of Stage-II increases. Out of the pairs so generated, the one with minimum sum of Stage-I and Stage-II times is considered as optimum and the corresponding assignment as the optimal assignment. A numerical illustration is given in the support of the theory. Also, the proposed algorithm is implemented and tested on a variety of test problems and the average run time for each problem is calculated.