@article{estruch2007minimal,
  title={Minimal distance-based generalisation operators for first-order objects},
  author={Estruch, V. and Ferri, C. and Hern{\'a}ndez-Orallo, J. and Ram{\'\i}rez-Quintana, M.},
  journal={Inductive Logic Programming, 16th International Conference,
               ILP 2006, Santiago de Compostela, Spain, August 24-27, 2006,
               Revised Selected Papers},
  pages={169--183},
  year={2007},
  series    = {Lecture Notes in Computer Science},
  volume    = {4455},
  publisher={Springer},
  ee        = {http://dx.doi.org/10.1007/978-3-540-73847-3_21}
}