@misc{W2109910161,
  author = {Richard S. Sutton and Doina Precup and Satinder Singh},
  title = {Between MDPs and semi-MDPs: A framework for temporal abstraction in reinforcement learning},
  year = {1999},
  howpublished = {Artificial Intelligence},
  doi = {https://doi.org/10.1016/s0004-3702(99)00052-1}
}