To make the problem more concrete, let the agent in question be an interactive planner. This framework breaks the knowledge up into tasks and methods .
Some tasks are atomic in nature.
In this case, the task refers to one or more of these operators or procedures instead of methods. These control relations define the actual algorithm that the method utilizes. For this reason, these tasks are known as leaf tasks . A task can be thought of as a function declaration in some programming language, annotated with predicates to define preconditions and predicates to define the relationship between input and output. One important exception to this analogy is that a task may be accomplished by more than one method or operator.