14 Important Ideas  Plan graph construction is polynomial time  Though construction can be expensive when there are many objects and hence many propositions  The plan graph captures important properties of the planning problem  Necessarily unreachable literals and actions  Possibly reachable literals and actions  Mutually exclusive literals and actions  Significantly prunes search space compared to POP style planners  The plan graph provides a sound termination procedure  Knows when no plan exists  Plan graphs can also be used for deriving admissible (and good non-admissible) heuristics  See your book (we may come back to this idea later)
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