@article{StructuralTractability,
  title = "A unified theory of structural tractability for constraint satisfaction problems",
  author = "David Cohen and Peter Jeavons and Marc Gyssens",
  year = "2008",
  journal = "Journal of Computer and System Sciences",
  note = "Earlier, uncorrected, version appears in Proceedings of IJCAI'05, pp. 72--77: \url{http://www.ijcai.org/papers/0521.pdf}",
  pages = "721-743",
  url = "http://www.comlab.ox.ac.uk/activities/constraints/publications/JCSSspreadcut.pdf",
  volume = "74",
  doi = "10.1016/j.jcss.2007.08.001",
}