@article{TractableConstraintsOrdered,
  title = "Tractable Constraints on Ordered Domains",
  author = "P.G.Jeavons and M.C.Cooper",
  year = "1995",
  journal = "Artificial Intelligence",
  number = "79(2)",
  pages = "327--339",
  url = "ftp://ftp.cs.rhul.ac.uk/pub/constraints/maxclos.ps",
}