- Abstract some details of the problem or actions.
- Solve the abstracted version.
- Extend the solution to the detailed version
- Work on satisfying important preconditions first
- Importance judged by:
- Length of plans for subgoals [ABSTRIPS, PABLO]
- Inter-goal relations [ALPINE]
- Distribution-based [HighPoint]
- Strong abstractions (with downward refinement property) are rare
- Effectiveness is planner-dependent
- Clashes with other heuristics such as “most constrained first”