@article{towardsminimaxonlinelearningwithunknown,
  title = {Towards Minimax Online Learning with Unknown Time Horizon},
  author = {Haipeng Luo and Robert E. Schapire},
  year = {2013},
  eprint = {1307.8187},
  archivePrefix = {arXiv},
  url = {http://arxiv.org/abs/1307.8187v2},
}