@article{JMLR:v19:17-684,
  author  = {Tomoyuki Obuchi and Yoshiyuki Kabashima},
  title   = {Accelerating Cross-Validation in Multinomial Logistic Regression with $\ell_1$-Regularization},
  journal = {Journal of Machine Learning Research},
  year    = {2018},
  volume  = {19},
  number  = {52},
  pages   = {1--30},
  url     = {http://jmlr.org/papers/v19/17-684.html}
}