@article{JMLR:v16:daniely15a,
  author  = {Amit Daniely and Sivan Sabato and Shai Ben-David and Shai Shalev-Shwartz},
  title   = {Multiclass Learnability and the ERM Principle},
  journal = {Journal of Machine Learning Research},
  year    = {2015},
  volume  = {16},
  number  = {72},
  pages   = {2377--2404},
  url     = {http://jmlr.org/papers/v16/daniely15a.html}
}