Solving Clustered Oversubscription Problems for Planning e-Courses

In a general setting, oversubscription in planning can be posed as: given a set of goals, each one with a utility, obtain a plan that achieves some (or all) the goals, maximizing the utility, as well as minimizing the cost of achieving those goals. In this paper, we present an application domain, automatic generation of e-learning courses design, that shows a variation of the oversubscription problem. Here, there is only one goal: generating a course design for a given student. However, in order to achieve the goal, the course design can include or not different kinds of activities, each one with a utility and cost. Furthermore, these activities are grouped into clusters, so that at least one of the activities in each cluster is needed, though many more can be used. Finally, these problems also have an overall cost threshold (usually in terms of student time). So we show several techniques for solving the clustered-oversubscription problem and their impact on plan-