@techreport{ccjz10:tr-galois,
  title = "An algebraic theory of complexity for valued constraints: {E}stablishing a {G}alois connection",
  author = "Cohen, D.A. and Creed, P. and Jeavons, P.G. and \v{Z}ivn\'y, S.",
  year = "2010",
  address = "Oxford, UK",
  month = "November",
  number = "CS-RR-10-16",
  url = "http://www.cs.ox.ac.uk/files/3564/RR-10-16.pdf",
}