An Efficient SMT Approach to Solve MRCPSP/max Instances with Tight Constraints on Resources

Abstract

The Multi-Mode Resource-Constrained Project Scheduling Problem with Minimum and Maximum Time Lags (MRCPSP/max) is a generalization of the well known Resource-Constrained Project Scheduling Problem. Recently, it has been shown that the benchmark datasets typically used in the literature can be easily solved by relaxing some resource constraints, which in many cases are dummy. In this work we propose new datasets with tighter resource limitations. We tackle them with an SMT encoding, where resource constraints are expressed as specialized pseudo-Boolean constraints and then translated into SAT. We provide empirical evidence that this approach is state-of-the-art for instances highly constrained by resources.