| Article ID: | iaor20082434 |
| Country: | United Kingdom |
| Volume: | 10 |
| Issue: | 2 |
| Start Page Number: | 139 |
| End Page Number: | 146 |
| Publication Date: | Apr 2007 |
| Journal: | Journal of Scheduling |
| Authors: | Brucker Peter, Kravchenko Svetlana A., Sourd Francis, Baptiste Philippe, Chrobak Marek, Drr Christoph |
| Keywords: | programming: linear |
We study the problem of preemptive scheduling of n jobs with given release times on m identical parallel machines. The objective is to minimize the average flow time. In this paper, we show that when all jobs have equal processing times then the problem can be solved in polynomial time using linear programming. Our algorithm can also be applied to the open-shop problem with release times and unit processing times. For the general case (when processing times are arbitrary), we show that the problem is unary NP-hard.