Realizing the Alternative Resources Constraint Problem with Single Resource Constraints

Alternative resource constraint problems have to be solved in practical applications where several resources are available for the activities to be scheduled. In this paper, we present a modular approach to solve such problems which is based on single resource constraints. Furthermore, we present a new sweeping algorithm which performs some “global” overload checking for the alternative resource constraint problem. To our knowledge, this is the first presentation where “sweeping”, a well-known technique in computational geometry, was used to perform this checking efficiently. For a practical evaluation of our approach, we implemented and integrated it in our Java constraint engine firstcs. We compared our implementation with the more general disjoint2 constraint in SICStus Prolog on some benchmark problems. These problems are random placement problems available online on the Internet.