Solving scheduling problems from high-level models

Jean-Noël Monette
2010 4OR  
of the Thesis Scheduling consists in deciding when a set of activities must be executed under different constraints, in order to optimize a given objective. The two main types of constraints are precedences between activities, and the availability of finite resources. Common objectives are to minimize the total duration, or to minimize the weighted sum of the tardiness of activities with respect to given due-dates. Scheduling problems are very varied, both in application domains and in featured
more » ... constraints. They have been a large area of research for decades. A lot of work has been undertaken to express, classify, and solve scheduling problems. Most of these problems are computationally hard to solve (in the sense of being NP-complete) and need complex algorithms (using techniques in the domains of Operations Research and Artificial Intelligence, such as e.g. Constraint Programming, Local and Heuristic Search, Mathematical Programming). But the difficulty lies also in the modeling of the problems, and the mapping between high-level, declarative models and low-level, procedural search techniques. The problem we are tackling is the gap between the high-level modeling of scheduling problems and their efficient resolution. This gap has several causes. First, most search techniques deal with more or less pure problems, and may not be easily adapted to solve problems with side constraints. Second, it requires a strong background in operations research to cast the problem to the right representation. Our goal is to facilitate the work of the user, such that no particular expertise is needed to solve a problem of scheduling. Our contributions in this direction are listed next: Acknowledgments First of all, I would like to thank Yves Deville for the 5 years he spent helping me and guiding me. I find him a very good advisor. He has a good balance between letting us free, and guiding us to avoid traps and pitfalls. It is also enjoyable to speak with him about subjects outside our research subjects. I thank also Pascal Van Hentenryck for his many ideas that really pushed me forward, for his reception during my stays at the Brown University, and all the interest he gave to my research. Many thanks goes to Pierre Schaus, which has been my office mate for so many years. He is a very nice person to work with. He always has plenty of ideas and of motivation.
doi:10.1007/s10288-010-0143-7 fatcat:xl2o2skrdzcjroge7ymc4rnxlm