The system's knowledge base is designed to reflect a hierarchical model of the domain, and its control and inference mechanisms encourage a mixed-initiative style of interaction between the computer and the user. Many planning systems assume that only the agent affects the state of the world and that the effects of actions are instantaneous. A skeletal-planning methodology is used to manage these constraints. A skeleton consists of a hierarchy of actions and their sequencing relations. The skeletal plans are based on treatment protocols developed through clinical trials.
Heuristics convert the skeletal plan to an actual plan for a specific patient.
Patients' past responses to treatment are a major determiner of future therapies. Since the treatment schedule may extend over many months, temporal reasoning is an important component of the system, although projection of actions into the future is not required. The Digital Library is published by the Association for Computing Machinery.