The Integration of Planning into Scheduling with OMP

AAAI Conferences 

Current planning and scheduling (P&S) literature exposes a trend to integrate both planning and scheduling features in the aim of addressing more challenging real-world problems. Even if planning and scheduling have been usually handled independently using different methods and technologies, it could be easy to find strict connections between them. While in certain application domains the subdivision of the two problems as separate entities is quite motivated (see for example (Srivastava, Kambhampati, & Do 2001; Pecora & Cesta 2005)), in other domains such a clear separation of the planning and scheduling phase is more questionable. From one hand specialized scheduling capabilities are required in a planning engine as soon as non trivial resource constraints have to be taken in account: even if some approaches have pursued the idea to embed resource models directly into a planning engine, it is still not clear how non trivial problems over multi capacity and consumable resources can be afforded without exploiting the powerful capabilities of scheduling reasoners. From the other hand planning capabilities are required in a scheduling environment in order to deal with complex situations where paying attention only to resources capacity constraints is not enough to solve the problem. Very often, it could be necessary to guarantee also some logical orders between the activities that cannot be decided in advance when the scheduling problem is initially formulated. For instance, in several domains a resource could require setup activities whose position cannot be decided all at once but rather depends on the order that the scheduler chooses for other activities during problem solving. Several architectural approaches to integrate planning and scheduling problems exists: for instance O-PLAN (Currie & Tate 1991), IxTeT (Laborie & Ghallab 1995), HSTS (Muscettola et al. 1992), R