I didn’t mean interval encoding outperforms WAH, I agree that WAH or EWAH could be the best scheme for bitmap indexes. I have read Wu’s ACM paper(38 pages) and it really makes sense. If you have a high selectivity query, your effort should be small. But with interval coding, your effort ...

According to Wu’s paper, the WAH space complexity is 2N words for most datasets, 4N for the worst case. Note it is 2N words,that is 64N bits. My m*b/2*n is in bits!m and b are both very small, isn’t it? I can’t image m L^(m/2)/2, since L can be a very big number. Chan would not be ...

where can I find the description of EWAH? EWAH is not an important contribution, nevertheless… see this paper: Sorting improves word-aligned bitmap indexes See also my slides: http://www.slideshare.net/lemire/all-about-bitmap-indexes-and-sorting-them What is hierarchical coding? where can I fi...

The general idea behind WAH is sound and that’s what people should be using. Not necessarily WAH itself, but some variant. For example, we decided to use EWAH. (Note that WAH itself is patented.) Chan’s interval encoding is a bit of a problem because it will generate an incompressible in...

@Haran The data is most certainly not available in structured format. Nor is it available from one place only. Even if you can parse the papers to recognize the citations, you have to link the citations to the papers. That is not easy. There are many ways to cite a paper, and several papers have alm...

@Dupuis Scopus and/or Web of Science do a few of the things you’re looking for, not perfectly, but it’s a start. I would argue it is a *bad* start. Scopus knows about 11 of my papers, and one of them is not from me, so it knows about 10 of my papers. It thinks that my 2000 paper “W...

According to a recent study, students do better if they skip class and listen to the podcasts. The article has been discussed in the New Scientist and the New York Times, but here is a direct quote: Results indicated that students in the podcast condition who took notes while listening to the podcas...

Andre Vellino pointed me to this article: Will the recession affect higher education? Short answer: yes. Interesting bites: If you think education has historically had a hard time competing for public dollars with health care, you ain’t seen nothing yet. (…) institutions will need to fin...

I have had some experience reviewing scholarship requests from graduate students. Here are a few pointers: For God’s sake! Know why you are going to graduate school! Boring reasons include: learning more about your favorite field, wanting to become a professor one day, finding your topic fasci...

On December 10th 2008, Denis G. Rancourt, a full professor in Physics at the University of Ottawa was banned from his campus. Why? Because he refused to grade students: Problems between university brass and Rancourt began eight months ago when he gave every student in his physics class an A+ after h...