@article{JMLR:v18:16-299,
  author  = {Jie Shen and Ping Li},
  title   = {A Tight Bound of Hard Thresholding},
  journal = {Journal of Machine Learning Research},
  year    = {2018},
  volume  = {18},
  number  = {208},
  pages   = {1--42},
  url     = {http://jmlr.org/papers/v18/16-299.html}
}