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ACM Transactions on Information Systems (TOIS), Volume 21 Issue 2, April 2003

Performance issues and error analysis in an open-domain question answering system
Dan Moldovan, Marius Paşca, Sanda Harabagiu, Mihai Surdeanu
Pages: 133-154
DOI: 10.1145/763693.763694
This paper presents an in-depth analysis of a state-of-the-art Question Answering system. Several scenarios are examined: (1) the performance of each module in a serial baseline system, (2) the impact of feedbacks and the insertion of a logic prover,...

A hierarchical access control model for video database systems
Elisa Bertino, Jianping Fan, Elena Ferrari, Mohand-Said Hacid, Ahmed K. Elmagarmid, Xingquan Zhu
Pages: 155-191
DOI: 10.1145/763693.763695
Content-based video database access control is becoming very important, but it depends on the progresses of the following related research issues: (a) efficient video analysis for supporting semantic visual concept representation; (b) effective video...

Region proximity in metric spaces and its use for approximate similarity search
Giuseppe Amato, Fausto Rabitti, Pasquale Savino, Pavel Zezula
Pages: 192-227
DOI: 10.1145/763693.763696
Similarity search structures for metric data typically bound object partitions by ball regions. Since regions can overlap, a relevant issue is to estimate the proximity of regions in order to predict the number of objects in the regions'...