Title: Consistent query answers in inconsistent probabilistic databases

Meeting Room: No.1 Meeting room, 1st Floor of PKU-ICST Building.

Time: 9:15 am-11:00 am, June 4th, 2012

Abstract:

Efficient and effective manipulation of probabilistic data has become increasingly important recently due to many real applications that involve the data uncertainty. This is especially crucial when probabilistic data collected from different sources disagree with each other and incur inconsistencies. In order to accommodate such inconsistencies and enable consistent query answering (CQA), in this paper, we propose the all-possible-repair semantics in the context of inconsistent probabilistic databases, which formalize the repairs on the database as repair worlds via a graph representation. In turn, the CQA problem can be converted into one in the so-called repaired possible worlds (w.r.t. both repair worlds and possible worlds). We investigate a series of consistent queries in inconsistent probabilistic databases, including consistent range queries, join, and top-k queries, which, however, need to deal with an exponential number of the repaired possible worlds at high cost. To tackle the efficiency problem of CQA, in this paper, we propose efficient approaches for retrieving consistent query answers, including effective pruning methods to filter out false positives. Extensive experiments have been conducted to demonstrate the efficiency and effectiveness of our approaches.

Bio:

Xiang Lian received the BS degree from the Department of Computer Science and Technology, Nanjing University, in 2003. He obtained the PhD degree in the Department of Computer Science and Engineering, Hong Kong University of Science and Technology, Hong Kong, in 2009. From 2009 to 2011, he worked as a post-doctoral fellow in the Department of Computer Science and Engineering, Hong Kong University of Science and Technology, Hong Kong. He is now an assistant professor in the Department of Computer Science at the University of Texas - Pan American. His research interests include query processing over uncertain databases, streaming time series, spatial databases and inconsistent probabilistic databases. More details about Dr. Xiang Lian can be founded at http://www.cs.panam.edu/~xlian/