@article{modeltheoreticcharacterizationsof,
  title = {Model-theoretic Characterizations of Existential Rule Languages},
  author = {Heng Zhang and Yan Zhang and Guifei Jiang},
  year = {2020},
  eprint = {2001.08688},
  archivePrefix = {arXiv},
  url = {https://arxiv.org/abs/2001.08688v1},
}