Solving MRCPSP by Constraint Programming

This paper solves the well-known multi-mode resource-constrained project scheduling problem (MRCPSP). The problem type is known to be NP-hard and has been solved using various exact as well as (meta-) heuristic procedures. By introducing constraint programming (CP) method, this problem is solved optimally and efficiently. First, a complete CP model for this problem is established. Next, IBM ILOG Script, a scripting language for combining CP models and interacting with them, is adopted to solve the original model with different data sets. Computational experiments carried out on randomly generated problem instances show high efficiency of solving process and good solution quality. The CP based method can solve instances of up to 300 tasks optimally and efficiently. All the constraints are satisfied explicitly and using a modeling language allows user imposed constraints to be easily added to the model. The results can be used as basis for heuristic methods.