@article{porteous2010applying,
  title={Applying planning to interactive storytelling: Narrative control using state constraints},
  author={Porteous, Julie and Cavazza, Marc and Charles, Fred},
  journal={ACM Transactions on Intelligent Systems and Technology},
  volume={1},
  number={2},
  pages={1--21},
  year={2010},
  publisher={ACM}
}