@phdthesis{Zivny09:phdthesis,
  author = "Stanislav \v{Z}ivn\'{y}",
  school = "Oxford University Computing Laboratory",
  title = "The Complexity and Expressive Power of Valued Constraints",
  url = "http://zivny.cz/publications/SZivny09DPhil.pdf",
  year = "2009",
}