@inproceedings{AlgebraicApproach,
  title = "An algebraic approach to multi-sorted constraints",
  author = "Andrei Bulatov and Peter Jeavons",
  year = "2003",
  booktitle = "Proceedings of CP'03",
  note = "Earlier version available as an OUCL Research Report : \url{http://web.comlab.ox.ac.uk/oucl/publications/tr/rr-01-18.html}",
  number = "2833",
  pages = "183--198",
  series = "Lecture Notes in Computer Science",
  url = "http://www.cs.ox.ac.uk/activities/constraints/publications/CP03multisorted.pdf",
}