Representation and Control in Ixtet, a Temporal Planner
Malik Ghallab, Hervé Laruelle · 1994
This paper presents a temporal planner, called IxTeT. It focuses on the representation and control issues, arguing for a compromise between the expressiveness and the ei~ciency of the search. The representation re-lies on a point-based reified logic, associated to mldti-valued domain attributes. Hieraxchical planning oper-ators ot~er an expressive description, with parallelism, durations, effects and conditions at various moments of the action. Time in the input scenario enables to take into account predicted forthcoming events and to plan in a dynamic world. A compilation procedure checks the consistency of the operators specified by the user. The control relies on the use of causal-links, A, algorithm, and an extended least-commitment strat-egy. It uses two important procedures, called C~feasi-bility " and "satisfiability =, dealing respectively with goal decomposition and conflict resolution: