@article{cz12:jair,
  title = "Tractable triangles and cross-free convexity in discrete optimisation",
  author = "Martin C. Cooper and Stanislav \v{Z}ivn\'y",
  year = "2012",
  journal = "Journal of Artificial Intelligence Research",
  pages = "455--490",
  url = "http://zivny.cz/publications/cz12jair-preprint.pdf",
  volume = "44",
  doi = "10.1613/jair.3598",
}