Recent Publications

You can find my work on arXiv, on Google Scholar, on DBLP, on the ACM Portal, on R Libre and elsewhere.

  • Consistently faster and smaller compressed bitmaps with Roaring
    Software: Practice and Experience Volume 46, Issue 11, pages 1547-1569, November 2016

    Details PDF Code Project

  • SIMD Compression and the Intersection of Sorted Integers
    Software: Practice and Experience 46 (6), 2016

    Details PDF Code

  • Decoding billions of integers per second through vectorization
    Software: Practice & Experience 45 (1), 2015

    Details PDF Code

  • Measuring academic influence: Not all citations are equal
    Journal of the Association for Information Science and Technology 66 (2), 2015

    Details PDF Dataset

  • Sorting improves word-aligned bitmap indexes
    Data & Knowledge Engineering 69 (1), 2010

    Details PDF Code

  • Faster retrieval with a two-pass dynamic-time-warping lower bound
    Pattern recognition 42 (9), 2009

    Details PDF Code

  • Tag-Cloud Drawing: Algorithms for Cloud Visualization
    Tagging and Metadata for Social Information Organization (WWW 2007)

    Details PDF Slides Code Dataset

  • Slope One Predictors for Online Rating-Based Collaborative Filtering
    In SIAM Data Mining (SDM 2005), Newport Beach, California, April 21-23, 2005

    Details PDF



Roaring Bitmaps

Fast compressed bitmaps, widely used. (picture: Edge Earth)


I supervise graduate students at TÉLUQ et at UQAM. I also co-supervise students the University of New Brunswick, at the École Polytechnique and at Concordia University.

Recent graduates:

  • Shany Carle (M.Sc., 2017);
  • Joseph Tumusenge (M.Sc., 2016);
  • Samy Chambi (Ph.D., 2016, with Robert Godin);
  • Jing Li (Ph.D., 2016, with Yuhong Yan);
  • Claude Corriolan (M.Sc., 2016);
  • Hazel Webb (Ph.D., 2010, with Owen Kaser).

I’m recruiting graduate students and postdoctoral fellows for my lab. If you love writing crazily fast software and want to come to Montreal, drop me a line. Link to an impressive GitHub profile is an asset.


I have served in the program committee of several international conferences such as

  • ACM Conference on Information and Knowledge Management (ACM CIKM)
  • ACM Conference on Web Search and Data Mining (ACM WSDM)
  • ACM Conference on Information Retrieval (ACM SIGIR)
  • ACM Conference on Recommender Systems (ACM RecSys)
  • ACM/IEEE Joint Conference on Digital Libraries (JCDL)

I recently served on the following program committees:

  • SPIRE 2017 - 24th International Symposium on String Processing and Information Retrieval (September 26-29, 2017; Palermo, Italy)
  • WWW 2018 - Twenty-seventh International WWW Conference (April 23-27 2018; Lyon, France)
  • DOLAP 2018 - Nineteenth International Workshop On Design, Optimization, Languages and Analytical Processing of Big Data (March 26–29, 2018; Vienna, Austria)
  • CIKM 2017 - Twenty-Sixth ACM International Conference on Information and Knowledge Management (November 6-10, 2017; Singapore)

I was an external referee for the following Ph.D. students:

  • Mohammed Shaaban at Université Pierre et Marie Curie (2017) - supervised by Patrick Garda.
  • Mehdi Boukhechba at UQAC (2016) - supervised by Abdenour Bouzouane and Charles Gouin-Vallerand.
  • Hicham Assoudi at UQAM (2016) - supervised by Hakim Lounis.
  • Khaled Dehdouh at Lyon 2 (2015) - supervised by Omar Boussaid.
  • Martin Leginus at Aalborg University (2015) - supervised by Peter Dolog.
  • Ahmad Taleb at Université Concordia (2011) - supervised by Todd Eavis.

I served as a committee member for several funding bodies:

  • FQRNT: review committee 03F (theoretical computer science) since 2007.
  • FQRNT: review committee 309 (team projects in computer science) since 2006.
  • NSERC: Research Tools and Instruments Grants Program (2012-2015)
  • NSERC: Computer Science Evaluation Group (EG 1507) for the Discovery Grants Program (2018-2020)