@article{nelson2006declarative,
  title={Declarative optimization-based drama management in interactive fiction},
  author={Nelson, Mark J. and Mateas, Michael and Roberts, David L. and Isbell, Charles L.}, 
  journal={IEEE Computer Graphics and Applications}, 
  volume={26}, 
  number={3}, 
  pages={32-41}, 
  year={2006}
}