Course assignment problem with interval requested workload

While dealing with the course assignment of all instructors in the department of Mathematics and Computer Science, faculty of Science, Chulalongkorn University, we found out some flexibility in the requested teaching workload. Instructors had been asked to provide their requested teaching workload and preference subjects for each coming up semester. These data were used to create the course assignment by hand, which had no guarantee in the sense of optimality. More troubles happened when some instructors would like to change their promising teaching workload to be larger or smaller than their original requested teaching workload, due to various reasons. This creates an uncertain range of possible requested teaching workload and may lead to a different course assignment. The possible requested workload of each instructor has the sense of ignorance fuzzy/possibility to it. We apply some ideas in interval linear program to work with this research, which is an interval mixed binary linear program, to be able to inform the subjects and the amount of workload that each instructor would be assigned to teach under the objective of optimizing the overall preferences and extra/remaining workload using the pessimistic and optimistic approaches.