Sigma encoded inverted files.

@inproceedings{trotman-2007-sigma, author = {Andrew Trotman and Vikram Subramanya}, editor = {M\'{a}rio J. Silva and Alberto H. F. Laender and Ricardo Baeza-Yates and Deborah L. McGuinness and Bj{\o}rn Olstad and {\O}ystein Haug Olsen and Andr\'{e} O. Falc\~{a}o}, title = {{Sigma encoded inverted files}}, booktitle = {{Proceedings of the Sixteenth ACM Conference on Information and Knowledge Management, CIKM 2007, Lisbon, Portugal, November 6-10, 2007}}, pages = {983--986}, publisher = {ACM}, year = {2007}, url = {https://doi.org/10.1145/1321440.1321591}, doi = {https://doi.org/10.1145/1321440.1321591} }