Goal interaction in planning
= Goal interaction in planning
Two subgoals interact when actions needed for one can establish, obstruct or delete facts needed for the other. A <plan> for each subgoal separately need not combine into a <plan> for their <conjunction>. Preparing the world before committing to a subgoal, revising an earlier subplan or temporarily undoing an achieved fact can all be necessary. <Goal-by-goal planning> may therefore be incomplete.