@article{cz11aij,
  title = "Hybrid tractability of valued constraint problems",
  author = "Martin C. Cooper and Stanislav \v{Z}ivn\'y",
  year = "2011",
  journal = "Artificial Intelligence",
  month = "June",
  number = "9-10",
  pages = "1555--1569",
  url = "http://zivny.cz/publications/cz11aij-preprint.pdf",
  volume = "175",
  doi = "10.1016/j.artint.2011.02.003",
}