@article{MaximalTractable,
  title = "A maximal tractable class of soft constraints",
  author = "David Cohen and Martin Cooper and Peter Jeavons and Andrei Krokhin",
  year = "2004",
  journal = "Journal of Artificial Intelligence Research",
  note = "Earlier version appeared in: Proceedings of IJCAI'03, pp. 209-214: \url{http://www.comlab.ox.ac.uk/activities/constraints/publications/IJCAI03submodular.pdf}",
  number = "22",
  pages = "01/01/22",
  url = "http://www.jair.org/papers/paper1400.html",
}