Incremental Propagation Rules for Precedence Graph with Optional Activities and Time Windows

Constraint-based scheduling is a powerful tool for solving real-life scheduling problems thanks to a natural integration of special solving algorithms encoded in global constraints. The filtering algorithms behind these constraints are based on propagation rules modelling some aspects of the problems, for example a unary resource. This paper describes new incremental propagation rules integrating a propagation of precedence relations and time windows for activities allocated to a unary resource. Moreover, the rules also cover so called optional activities that may or may not be present in the final schedule.