@inproceedings{OPICALP09,
  title = "Tractable Optimization Problems through Hypergraph-Based Structural Restrictions",
  author = "Georg Gottlob and Gianluigi Greco and Francesco Scarcello",
  year = "2009",
  address = "Rhodes, Greece",
  booktitle = "Proceedings of the 36th International Colloquium on Automata, Languages and Programming",
}