@article{hardnessresultsforapproximatepurehorn,
  title = {Hardness Results for Approximate Pure Horn CNF Formulae Minimization},
  author = {Endre Boros and Aritanan Gruber},
  year = {2012},
  eprint = {1204.3529},
  archivePrefix = {arXiv},
  url = {http://arxiv.org/abs/1204.3529v3},
}