@inproceedings{ijcai2009p122,
  title     = {Next Steps in Propositional Horn Contraction},
  author    = {Booth, Richard and Meyer, Thomas Andreas and Varzinczak, Ivan José},
  booktitle = {Proceedings of the Twenty-First International Joint Conference on
               Artificial Intelligence, {IJCAI-09}},
  publisher = {International Joint Conferences on Artificial Intelligence},
  editor    = {Hiroaki Kitano},
  pages     = {702--706},
  year      = {2009},
  url       = {https://ijcai.org/proceedings/2009/122},
}