@InProceedings{KazutoshiUmemoto:2020,
  author = {Kazutoshi Umemoto, Tova Milo, and Masaru Kitsuregawa},
  title = {Toward Recommendation for Upskilling: Modeling Skill Improvement and Item Difficulty in Action Sequences},
  booktitle = {36th IEEE International Conference on Data Engineering (ICDE 2020)},
  year      = {2020},
  pages     = {169-180},
}