@article{GKK+21,
  author  = {Gourdeau, Pascale and Kanade, Varun and Kwiatkowska, Marta and Worrell, James},
  title   = {On the Hardness of Robust Classification},
  journal = {Journal of Machine Learning Research},
  year    = {2021},
  volume  = {22},
  number  = {273},
  pages   = {1-29},
  url     = {http://jmlr.org/papers/v22/20-285.html}