@InProceedings{cai-et-al:icaps-2009,
  author =       "Dunbo Cai and J{\"o}rg Hoffmann and Malte Helmert",
  title =        "Enhancing the Context-Enhanced Additive Heuristic with Precedence Constraints",
  booktitle =    "Proceedings of the 19th International Conference on Automated
                  Planning and Scheduling (ICAPS 2009)",
  publisher =    "AAAI Press",
  pages =        "50--57",
  year =         "2009",
  subproject =   {S1},
  access =       {open},
  bibtex =       {cai.icaps09.bib},
  pdf =          {cai.icaps09.pdf},
  abstract =     {Recently, Helmert and Geffner proposed the context-enhanced additive
heuristic, where fact costs are evaluated relative to context states
that arise from achieving first a pivot condition of each operator. As
Helmert and Geffner pointed out, the method can be generalized to
consider contexts arising from arbitrary precedence constraints over
operator conditions instead. Herein, we provide such a generalization.
We extend Helmert and Geffner's equations, and discuss a number of
design choices that arise. Drawing on previous work on goal orderings,
we design a family of methods for automatically generating precedence
constraints. We run large-scale experiments, showing that the
technique can help significantly, depending on the choice of
precedence constraints. We shed some light on this by profiling the
behavior of all possible precedence constraints, using a sampling
technique.},
}