@INPROCEEDINGS{mpv10,
  author = {M. Benedikt and G. Puppis and H. Vu},
  title = {Positive Higher-order Querier},
  booktitle = {Proceedings of the 29th ACM SIGMOD-SIGACT-SIGART Symposium on Principles of Database Systems (PODS)},
  year = {2010},
  pages = {27-38},
  publisher = {ACM}
}