@techreport{Zivny08:sub-tr,
  title = "Which submodular functions are expressible using binary submodular functions?",
  author = "Stanislav \v{Z}ivn\'y and Peter G. Jeavons",
  year = "2008",
  address = "Oxford, UK",
  institution = "OUCL",
  month = "June",
  number = "RR-08-08",
  url = "http://zivny.cz/publications/zj08sub-tr.pdf",
}