@article{JMLR:v18:16-212,
  author  = {Weiwei Liu and Ivor W. Tsang and Klaus-Robert Müller},
  title   = {An Easy-to-hard Learning Paradigm for Multiple Classes and Multiple Labels},
  journal = {Journal of Machine Learning Research},
  year    = {2017},
  volume  = {18},
  number  = {94},
  pages   = {1--38},
  url     = {http://jmlr.org/papers/v18/16-212.html}
}