Which of the following is not a component of the classic Planning Definition?

Answer: 'Domain' is not a component of the classic planning problem.

Classic planning problem components:

• Initial state (Init): the starting facts about the world from which planning begins.

• Actions (operators): the set of actions that can change the state; they define preconditions and effects used during planning.

• Goal: the conditions or state that the planner must achieve.

Why 'Domain' isn't a component: The domain describes the general model—action schemas, predicates, and types—used across many planning problems. It is part of the domain model, not one of the elements that define a single planning instance (which are initial state, actions, and goal).

Therefore, 'Domain' is the correct choice as the item that is not a component of the classic planning problem.